Essentials for Survival

Hello, learners! Welcome to an exciting world of how things move. in both living and the non-living environment, there are interesting processes called diffusion and osmosis. These processes involve the natural movement of particles, whether they are gases, liquids or solids. By studying how substances move in both biotic (living) and abiotic (non-living) media, we can gain a better understanding of how our universe works! In this section we will look at identification of real- life examples of diffusion and osmosis explain how they are relevant to those situations as well as conduct a simple experiment to demonstrate diffusion as well as osmosis and interpret the results. So, let us embark on a journey to explore the captivating world of diffusion and osmosis and their significance in both living and non-living systems.

At the end of this section, you will be able to:

• Appreciate the movement of substances in biotic and abiotic media.

• Design, model, and explain the process of osmosis and indicate its application in everyday life.

KEY IDEAS

• Diffusion is the process of particles or molecules spreading out or dispersing from an area of high concentration to an area of low concentration. The movement of the particles is spontaneous, unpredictable, and irregular.

• Active transport is a process that happens inside living cells to move substances from an area of lower concentration to an area of higher concentration. It is like going against the flow.

• Osmosis involves the movement of water (solvent) molecules from where there is more water (dilute solution) across a selectively permeable membrane to where there are less water molecules (concentrated solution).

• A dilute solution contains more water molecules (solvent) compared with the solute molecules, while a concentrated solution has more solute molecules compared with solvent molecules.

• Osmosis occurs in both plant and animal cells as well as in non-living tissues.

• A selectively permeable membrane allows some substances to pass through and prevents others from passing through it.

Concepts of Diffusion

Diffusion refers to the movement of molecules from an area of high concentration to an area of low concentration until the molecules are evenly distributed. The driving force behind diffusion is the concentration gradient, which is the difference in concentration between two regions. Diffusion always tends to equalise the concentration gradient leading to a uniform distribution of molecules and equal concentration throughout space or solution.

Examples of Diffusion in Living and Non-Living Cells:

1. Diffusion in Living Cells

a. Oxygen diffuses from areas of high concentration (such as the blood) into cells where its concentration is lower. This process is crucial for cellular respiration, where cells use oxygen to produce energy.

b. After cellular respiration, carbon dioxide, a waste product, accumulates in cells and diffuses out into the blood, where its concentration is lower.

This diffusion process helps to remove carbon dioxide from the cells and transport it to the lungs for exhalation.

c. Glucose, a primary energy source, diffuses into cells from areas of higher concentration (like the blood) to areas of lower concentration (inside the cells). This diffusion is often facilitated by specific transport proteins in the cell membrane, ensuring cells receive the glucose needed for energy production through glycolysis and other metabolic pathways.

Note: Facilitated diffusion is a process that allows substances to move in and out.

Of cells without using energy. It uses special proteins to help larger molecules cause the cell membrane, making it easier for them to get in and out. Glycolysis is the conversion of glucose to a high-energy molecule.

Below is a link to a video on diffusion in living cells. Click on the link to watch it.

https://www.youtube.com/watch?v=TRP3jCmkYiM

2. Diffusion in Non-Living Cells

a. If you leave a cup of hot chocolate on the table, you will notice that the steam rises and the aroma spreads in the air. This is because the hot chocolate particles move through diffusion, spreading out and mixing with the air particles.

b. When you add a spoonful of sugar to a cup of tea or coffee without stirring it, the sugar particles dissolve and spread throughout the liquid.

This happens because of diffusion, where the sugar particles move from a higher concentration (the spoonful) to a lower concentration (the rest of the liquid).

The examples above show how diffusion is a natural process that happens in both living and non-living cells, allowing particles to spread out and fill the available space.

Factors that Affect Diffusion Dear learner, click on the links below to watch the videos and describe your observations.

https://www.youtube.com/watch?v=E30DSfmAW4s https://www.youtube.com/watch?v=lxHMJaXOzP4

Activity 3.1

Describe and explain how each of the following factors affects the rate of diffusion.

1. Concentration gradient

2. Temperature

3. Particle size/molecular weight

4. Nature of media through which the diffusion occurs.

Activity 3.2: Demonstrating the spread of permanganate ions in solution Aim: The purpose of this demonstration is to show how particles move from an area of high concentration to an area of low concentration; the process of diffusion.

Materials needed: Beaker, water, potassium permanganate crystal and spatula.

Procedure

1. Fill the beaker with water.

2. Put a piece of potassium permanganate crystal at the bottom of the beaker containing water using a spatula. Be careful so that the water is not overly disturbed and that the crystal is positioned at the bottom of the beaker without much mixing.

3. Observe what happens over a few minutes. Describe and explain your observations.

Solutions can be found in Annex 1.

4. Extension task: Repeat this experiment with colder water, what do you predict will happen? Conduct the experiment to test your hypothesis.

Fig. 3.1: Process of diffusion using potassium permanganate crystal.

The video link below will give you a better understanding:

https://www.youtube.com/watch?v=mNlFmvx8o7Y

Activity 3.3: Demonstration of diffusion in gases using perfume Aim: To investigate the diffusion of perfume molecules through air.

Material needed: A bottle of inexpensive perfume.

Procedure:

1. Pour a small volume of perfume onto a piece of tissue and leave it in one corner of the classroom or open a bottle of perfume and leave it in a corner of the classroom.

Note: Spraying is not suitable for demonstrating the effect of diffusion.

2. Raise your hands when you can smell the perfume.

3. Describe and explain how your location and the time taken to smell the perfume are related. See possible solutions in Annex 3.1.

Fig. 3.2: Demonstration of diffusion by learners Application of Diffusion in Everyday Life Now learners, observe the following everyday activities and point out those you are very familiar with:

Perfume/Cologne: When you spray perfume or cologne onto the skin, the scent particles evaporate from the skin and diffuse through the air spreading from an area of high concentration (your skin) to an area of low concentration (the surrounding space).

Cooking: During cooking, food particles diffuse through the kitchen and sometimes beyond, allowing you to smell the food even if you are not standing directly over the stove. The food particles’ movement in the air gives the food its aroma.

Room Fresheners: Air fresheners or diffusers release fragrance into the air. The fragrance molecules disperse and diffuse throughout the room, creating a pleasant scent.

Tea/Coffee Brewing: When you place a tea bag or coffee grounds in hot water, the flavour compounds diffuse from the concentrated source into the surrounding liquid resulting in a flavoured beverage.

Oxygen and Carbon Dioxide Exchange: In the human body, diffusion is vital for gas exchange in the lungs. Oxygen from the inhaled air diffuses from the lungs into the bloodstream, while Carbon Dioxide diffuses into the lungs to exhale.

Hello learner, we hope you enjoyed the demonstration about diffusion in your previous lesson. You are going to experience another interesting phenomenon which also talks about movement of substances both in living and non-living things. This process is osmosis. Without osmosis many biological systems may not function. For example; plants will find it difficult to absorb water through their root hairs and may eventually die.

Osmosis is defined as the process by which solvent (water) molecules move from a dilute solution to a concentrated solution across a selectively permeable membrane. In effect, there is a net movement of water molecules across a selectively permeable membrane from an area of high concentration to an area of low concentration (of the water molecules). The selectively permeable membrane could be a living or non-living tissue.

Osmosis does not require energy from the cell to occur. It takes place naturally to ensure that concentration of water molecules on both sides of the selectively permeable membrane is equal.

The direction and rate of osmosis depends on the relative concentration of solutes on either side of the membrane.

Several factors affect the rate of osmosis. Notable amongst them are concentration gradient, temperature (greater temperature leads to a faster rate of osmosis) and presence of selectively permeable membrane.

Now learner, observe the illustration in Fig 3.3 closely and carry out the tasks in

Activity 3.4 alone or with your friends.

Fig 3.3: Illustration of Osmosis

Activity 3.4: Osmosis at home.

1. Name a common household substance that contains solvent molecules.

2. Name a common household substance that contains solute molecules.

3. (a) From the illustration, which molecules are moving?

(b ) In which direction are the molecules moving?

4. Describe the solutions A and B.

5. What process is causing the molecules identified in 3(a) to move?

Activity 3.5: Quick or slow swell.

Place a small handful of raisins or any dried fruits into a clear cup of water and take a photograph of them. Leave them for 24 hours and then take a new photograph.

Compare the appearance of the raisins before and after the experiment. Write a brief explanation of your observations.

Good, I believe you have got a clear idea of osmosis.

Activity 3.6: Movement of molecules.

Research on YouTube to give you more insight into osmosis with respect to movement of molecules.

1. https://www.youtube.com/watch?app=desktop&v=sUpFhbHo9lQ

2. https://www.youtube.com/watch?v=qGALyEW4ZFY

3. https://www.youtube.com/watch?v=30yV3RaU03g 1 2 3

Activity 3.7: Investigating osmosis in model cells with different internal water concentrations.

Aim: To investigate the process of osmosis on model cells with different internal water concentrations immersed in pure water/distilled water.

Note: The selectively permeable membrane used here as model cell is the Visking tubing.

Materials needed: 4 beakers/transparent containers, sugar/sucrose solution of concentrations 5%, 10% and 15% (weight by volume), water, Visking tubing, scissors, funnel, measuring tape, string and a ruler.

Fig (a): Investigating osmosis in a model cell using Visking tubing.

Procedure:

1. Fill each beaker/transparent container with pure water almost to the brim.

2. Cut equal lengths (12cm) of Visking tubing.

3. Tie one end of each piece of Visking tubing using string.

4. With the help of a funnel, pour pure/distilled water into the first piece of tubing and tie the other end.

5. Measure the circumference of the filled tubing using more string and the ruler and place the model into one of the beakers/transparent containers.

6. In the same way fill the next piece of Visking tubing with 5% sucrose

solution and place it in beaker 2.

7. Repeat for 10% sugar/sucrose and 15% sugar/sucrose solution and place them into beaker/transparent containers 3 and 4 respectively.

8. Leave the experiment for 24 hours and measure again the circumference of the model cells.

9. Observe how the model cell feels in comparison to the beginning of the experiment.

10. Record your results in the table given.

Note: The model cells contain different sucrose solutions and therefore different water concentrations. 0% sucrose has the highest water concentration, and 15% sucrose has the lowest water concentration. Water can move freely into or out of the Visking tubing but sucrose cannot.

Good. Now input your results into Table 3.1.

Observation/Results:

Table 3.1

Beaker Visking

tubing containing Circumference at start Circumference after 24 hours Firmness of model cell 1 Water 2 5% sucrose 3 10% sucrose 4 15% sucrose Explanation: Explain your observation from the results obtained above.

Let’s proceed to the next activity.

Activity 3.8: Investigating osmosis in plant/living tissues.

Aim: To investigate osmosis in plant tissues.

Materials you will need: Potato, borer/knife, sucrose solution (0%, 5%, 10%, 15%), 4 beakers, measuring cylinder, ruler, weighing balance.

Procedure:

(Note: you are welcome to adapt the procedure to investigate different solutes and/or different living tissues. You may also choose to use samples of different dimensions. Carry out your own research using the internet to design an experiment that will produce conclusive results. Alternatively, follow the method below):

1. Make up the four concentrations of sucrose solutions.

2. Pour 50cm³of pure/distilled water into beaker 1, 50cm³of 5% sucrose into beaker 2, 50cm³of 10% sucrose into beaker 3, 50cm³of 15% sucrose

solution into beaker 4.

3. Use the borer to remove 4 cylinders from the potato.

4. Cut the potato cylinder into 3cm lengths and dry with a paper towel.

5. Measure the mass, diameter, and length of each potato piece.

6. Record the results.

7. Place one potato cylinder into each beaker.

8. Leave for 24 hrs.

9. Record the mass, diameter, and length of each potato cylinder.

Water 5% sucrose 10% sucrose 15% sucrose Fig (b): Investigating osmosis in plant tissue Now record your results in Table 3.2 Observation/Results:

Table 3.2

Data analysis:

For each concentration of sucrose solution:

1. a. Calculate the percentage change in mass.

Hint: percentage changes can be found by finding the difference between the original value and the new value, then dividing this by the original value.

Multiply your result by 100 to find the percentage change. Note that if the new value is less than the original value then the difference is negative and therefore the percentage change is also negative.

b. Calculate the percentage change in length.

c. Calculate the percentage change in diameter.

d. Explain your observations.

2. Draw a line graph to present some of the results with sucrose concentration on the x-axis and percentage change in mass (or length or diameter) on the y-axis.

3. Present your findings to the rest of your class in a 3-minute oral presentation using visual aids if possible. Ensure that everybody in your group has a role in the presentation.

Food Preservation: Osmosis is utilised in food preservation techniques such as pickling and curing. In these processes, salt or sugar is used to create a high concentrated solution, which draws water out of the food and the microorganisms present in the food. This removal of water inhibits the growth of bacteria and other spoilage-causing organisms, thus extending the shelf life of the food.

Below is a link that will explain the preservation process better to you:

https://www.youtube.com/watch?v=PKsTsmD6b1k Kidney Function: Osmosis is integral to the functioning of the kidneys, which filter waste products from the blood and regulate water and electrolyte balance. The movement of water and solutes across the renal tubules occurs through osmosis, allowing the kidneys to concentrate urine and reabsorb necessary substances back into the bloodstream.

Below are two links that will explain osmosis in kidney function better to you:

1. https://www.youtube.com/watch?v=vdNwdC7eCT0

2. https://www.youtube.com/watch?v=OEzKQmqV2WQ Brining: Brining is a process used to enhance the flavour and juiciness of meat, poultry, and fish. It involves soaking the food in a solution of salt and water.

During brining, osmosis occurs as the salt concentration in the brine is higher than the concentration of salt in the meat or fish. Water moves from the meat or fish into the brine, resulting in decreased moisture content and improved flavour.

Below are links that will explain osmosis in brining of meat better to you:

1. https://www.youtube.com/watch?v=povvINECyb0

2. https://www.youtube.com/watch?v=55W29p6sgJ0

Review Questions 3.1

1. A man walking behind the kitchen of a house was able to smell the nice aroma coming from the soup being prepared. Explain how he was able to smell the scent of the soup.

2. Give at least three examples of diffusion in everyday life.

3. When the weather is hot, and a baker is baking bread the aroma goes farther from the bakery. What is the explanation for this?

4. What role does diffusion play in biological systems?

Review Questions 3.2

1. A boy accidentally watered a potted plant with salt solution. The next morning it was found that the plant was dying. Suggest a possible means for him to revive the plant. Explain your answer.

2. In dry Harmattan seasons most plants with shallow roots usually do not survive. However, plants with deep roots do survive. Briefly explain why this is so.

3. Ama and Ali (group A) and Emefa and Adjetey (group B) were performing an experiment to demonstrate osmosis. With all other factors being equal, Group A used water at room temperature while Group B used warm water. Whose experiment will be faster and why?

This section explores the fascinating world of reproduction in both plants and humans. We will begin by examining the key parts of flowering plants and how they contribute to plant reproduction, including the differences between sexual and asexual reproduction and how seeds are dispersed. We’ll then trace the life cycle of a flowering plant. Moving on to humans, we will identify the main parts of the male and female reproductive systems, describe the process of sexual reproduction, explain the menstrual cycle, and analyse its significance in human reproduction, including the role of hormones.

At the end of this section, you will be able to:

• Explain reproduction in plants

• Reproduction in animals

• Explain the female menstrual cycle and show how that can be used to address reproduction-related issues

KEY IDEAS:

• Reproduction is the process by which living organisms give rise to younger ones of their own kind. There are two types of reproduction:

Sexual and Asexual.

• A flower is the reproductive structure of a flowering plant. The flower typically consists of four main parts, each of which plays its own role in reproduction.

• A seed is the mature ovule that contains the embryo, a food storage tissue called the endosperm, and a protective seed coat.

• Fruits develop from the ovary and surround and protect the seed(s).

• Seed Dispersal: The scattering of seed away from the parent plant. There are many methods of seed dispersal.

• Humans reproduce sexually, meaning that both male and female sex cells are involved in the production of offspring.

• The Menstrual Cycle refers to a natural monthly phenomenon experienced by women of reproductive age. This happens when an unfertilised egg is released from the ovaries and is discharged through the vagina as blood and mucus.

Today we’re going to explore the fascinating topic of plant reproduction. Have you ever wondered how flowers are able to create new plants? It’s a complex but beautiful process that we’re going to dive into together.

Activity 4.1: What is reproduction?

Research and fill in the blanks below.

Learners, reproduction can take place in ______ or in humans/animals.

Reproduction in plants is a fundamental biological process that allows plants to propagate and ensure the ____________ of their species. Through these mechanisms, plants can produce _________, disperse their genetic material, and colonise new habitats.

There are two types of reproduction: _________ reproduction and __________ reproduction.

Sexual Reproduction

Learners, just as we have a male and female coming together to reproduce, in plants sexual reproduction also involves a male and a female part coming together to reproduce offspring. Sexual reproduction in plants is, therefore, the process by which a male sex cell fuses with a female sex cell to form a zygote. These specialised reproductive cells are called gametes, which are involved in the fusion of genetic material. The key processes involved in sexual reproduction in plants are pollination, fertilisation, seed production and dispersal, germination, and subsequent growth.

In flowering plants, male and female reproductive structures can often be found in the same individual plant. The main organ of sexual reproduction is the flower.

Let’s take a closer look at the main components of a flower.

Activity 4.2

Using some real flower specimens (possibly gathered on a nature walk), such as hibiscus, bougainvillea, pride of Barbados and flamboyant, perform a plant dissection. If you have time, you should compare the structure of one type of flower with another. Use the diagram below to identify the different parts of the flower, then use online resources (or any others that your teacher has provided) to research the function of the parts specified in Table 1.

Fig. 4.1: Parts of a flower

Table 4.1

Part Structure Function

Sepals Petals

Stamens Stigma

Ovary So how do the pollen and ovules come together to create new seeds and offspring? This process is called pollination.

Pollination When pollinators visit the flower to feed on its nectar, they inadvertently pick up pollen on their bodies. As they fly from bloom to bloom, they transfer this pollen to the receptive stigmas.

Once the pollen lands on the stigma, it grows a tiny tube that extends down through the style and into the ovary. The sperm cells within the pollen then fuse with the egg cells in the ovules, fertilising them. This fertilisation process forms seeds, which contain embryos that can germinate and grow into new plants.

Activity 4.3

Draw a diagram or storyboard showing the stages of sexual reproduction in plants. Research and discuss the descriptions and explanations that should be added to each stage of the diagram; pollination, fertilisation, seed production and dispersal, germination, and subsequent growth.

Agents of Pollination

Pollination requires some agents or vectors to help transfer pollen from one flower to another. The agents can be:

1. Insects (and other invertebrates)

2. Wind

3. Animals (bats, birds, mammals, birds, reptiles)

4. Water Fig 4.2: Agents of pollination NB: Insects and wind are the major agents of pollination.

Table 4.2: Characteristics/Adaptations of Insect and Wind-Pollinated Flowers

Compared.

Insect-pollinated flowers Wind pollinated flowers Petals are brightly coloured to attract insects Petals, if present, are dull in colour Flowers are scented Flowers are not scented Have sticky stigma Have feathery stigma Have short and stout filaments Have long filaments Produces less pollen grains Produce abundant pollen grains See Annex 4.2 – Further Information for more detail on the advantages of wind and insect pollinators

Activity 4.4: Pollination Simulation Processes

Aim: To investigate the processes of pollination and the role of different pollination agents in the transfer of pollen grains Materials needed:

• Mobile phone or other recording devices

• Flower models or dissected flowers

• Pens, pencils and paper

• Pollinator models (e.g. bee, butterfly and hummingbird) Procedure:

1. Watch this video on pollination and discuss the key points before you start the activity below.

Pollination Explained (youtube.com)

2. In groups of 3-4 people, produce a short video demonstrating the process of a) wind pollination and b) insect pollination using 3D models or drawings to aid visualisation. You should speak over the video to describe what is happening during each step of the process.

3. If you are unable to create a video, you should instead act out the scenarios.

4. Present your video or play to the rest of the class.

5. Offer constructive feedback to your peers once you have seen their video or play.

Fertilisation Dear learners, let us now discuss in detail what fertilisation is. Fertilisation is the fusion of the nucleus of a male gamete with the nucleus of a female gamete to form a zygote. Fertilisation takes place in the ovule, which contains the female gamete - the ovum. Ovules are found inside the ovary. Each ovule contains an egg. When a mature pollen grain lands on a mature stigma, it absorbs water and nutrients from the stigma and swells up. The wall of the pollen grain ruptures, and a pollen tube protrudes which penetrates the stigma and grows through its tissues into the style. This is the germination of the pollen grain. The pollen tube nucleus moves to the tip of the pollen tube. The pollen tube enters the ovule through the area called the micropyle. The pollen grain travels to the egg and fuses with it resulting in fertilisation. The fertilisation results in zygote formation which later develops into a seed. Following fertilisation, the zygote starts to divide, and it eventually turns into an embryo within the seed. The embryo is kept latent in a seed capsule until the right environmental factors allow it to germinate and grow into a new plant.

Following fertilisation, the ovary swells and forms the fruit. The role of fruit is in seed dispersal. Fruit can be considered the mobile stage in a plant’s life cycle.

Some fruits are carried by the wind, others are explosive and fire seeds far from the mother plant, others are attractive to animals are eaten and the indigestible seeds are transported and deposited in animal faeces, other fruits are sticky and transported after sticking to the animal’s fur.

Fig.4.3:Fertilisation in Plants

Activity 4.5

Follow the QR code below to watch a video of an experiment that can be done in the lab to observe pollen germination.

Conclusion:

The experiment has demonstrated the intricate process of fertilisation in flowering plants, where the transfer of pollen, the growth of pollen tubes, and the eventual fusion of male and female reproductive cells lead to the formation of seeds, a crucial step in the plant’s life cycle. Understanding this process is essential for appreciating the remarkable adaptations and strategies employed by flowering plants to ensure their successful reproduction and propagation.

Activity 4.6: Comparing the Costs and Constraints of Sexual vs. Asexual Reproduction in Plants.

Note: this is a long-term experiment which should take place over several weeks.

Aim: To investigate the key disadvantages that plants face when relying on sexual reproduction, compared to asexual reproduction strategies.

Materials needed:

• Seeds or seedlings of two plant species, one that reproduces primarily sexually (bean seed) and one that reproduces asexually (cassava sticks)

• Potting soil and containers for growing the plants

• Measuring tools (e.g. ruler, scale, and stopwatch)

• Access to pollinators (e.g. beehive, butterfly enclosure) or ability to manually pollinate

• Notebook and pen/pencil for observations Procedure:

1. Plant the seeds/seedlings of the sexually reproducing and asexually reproducing plant species in separate containers with the same soil and growing conditions.

2. For the sexually reproducing plant introduce pollinators or manually pollinate to facilitate seed production.

3. Extension: Simulate environmental stresses, like nutrient deprivation or rapid climate changes, to observe how each species responds.

4. Monitor the growth, resource allocation, and reproductive output of each species over time, keeping notes in your notebook.

5. Write a conclusion including comments about the advantages and disadvantages of being a sexual or asexual reproducer (cost, time commitment and dependence on external factors are all important considerations).

Asexual Reproduction

Asexual reproduction is the mode of reproduction that does not involve the fusion of male and female gametes and produces individuals genetically identical to the parent. Asexual plant reproduction occurs through many modes including suckers, runners, bulbs, tubers, and layering. No flowers are required for this method. Asexual reproduction in plants is often termed vegetative propagation and can take place naturally or artificially.

Natural Asexual or Vegetative Reproduction

This method of propagation enables plants to reproduce without the need for seeds or the involvement of external agents like pollinators. Instead, new individuals are generated from specialised plant parts such as roots, stems, bulbs, or leaves.

Table 4.3: Natural Methods of Asexual Reproduction

Method Description

Runners and

Stolon Some plants grow horizontal stems called runners or stolon along the ground. At different points on these stems, new plants can grow from the nodes, forming clones of the parent plant. Examples include strawberries and spider plants.

Method Description

Rhizomes Rhizomes are underground stems that spread horizontally and produce new shoots and roots at the nodes. Plants like ginger and bamboo use rhizomes to grow and spread over large areas.

Bulbs and Tubers Certain plants store nutrients in underground structures called bulbs (like onions) or tubers (like potatoes). These structures can sprout and grow into new plants.

Fragmentation If a part of the plant breaks off, it can sometimes grow into a completely new individual. For example, pieces of succulents like aloe vera or jade plants can develop roots and shoots when placed in the right conditions.

Roots Some plants can produce new plants from modified roots called tubers. An example is the sweet potato.

Leaves In some plants, small new plants called plantlets can grow from the edges of detached leaves, like in the Bryophyllum plant.

Artificial Propagation

Artificial propagation refers to the deliberate human intervention in the reproductive processes of plants and animals to produce offspring under controlled conditions.

These methods are employed in various fields such as agriculture, aquaculture, and horticulture.

Artificial propagation allows people to grow more of the plants they want, often faster and more reliably than waiting for natural reproduction. This is important in agriculture to produce food crops, in gardening to grow ornamental plants, and in other fields where specific plants are needed.

Artificial Propagation Methods

In the following section, you will learn about various methods by which humans can artificially propagate plants and will perform experiments to replicate these.

The main mechanisms are:

1. Cuttings

2. Grafting

3. Layering

4. Micropropagation

Activity 4.7

Research the terms listed above and give a brief summary of the processes involved.

Activity 4.8: Vegetative Propagation of Plants through Cuttings Watch the following short videos on cuttings and perform the activity below:

1. (241) Asexual Reproduction | Vegetative Propagation : Cutting - YouTube

2. How to Propagate plant cutting ,Grow more trees by vegetative propagation (youtube.com) Fig 3.4: Cutting Method Aim: To investigate the process of vegetative propagation in plants using stem cuttings and to observe the factors that influence the success of this asexual reproduction method.

Materials needed:

• Healthy, mature parent plant (donor plant) of the species to be propagated

• Sharp, clean scissors or pruners

• Potting mix or rooting medium (e.g., perlite, vermiculite, or a combination)

• Small pots or containers with drainage holes

• Rooting hormone powder (optional)

• Clear plastic bag or propagation dome (optional)

• Water spray bottle

• Labels and markers Procedure:

1. Select a healthy, disease-free parent plant and identify the appropriate stem sections for taking cuttings.

2. Cut 4-6-inch stem segments, making a clean, diagonal cut just below a leaf node.

3. Remove the lower leaves, leaving only the top 2-3 leaves on the cutting.

4. Dip the cut end of the cutting in rooting hormone powder (optional).

5. Plant the cuttings in the prepared potting mix or rooting medium, ensuring the leaf node is buried.

6. Water the cuttings gently and place them in a warm, shaded location.

7. (Optional) Cover the cuttings with a clear plastic bag or propagation dome to maintain high humidity.

8. Monitor the cuttings regularly, keeping the soil moist but not waterlogged.

9. Observe for the development of new roots and shoots over the next few weeks, noting your findings with regards to:

a. Rooting success rate of the cuttings

b. Time taken for the development of new roots and shoots

c. Differences in rooting and growth between cuttings treated with and without rooting hormone

d. Variations in rooting and growth among different stem positions or plant species

e. Challenges or issues encountered, such as fungal infections or drying out of the cuttings

Activity 4.9:Vegetative Propagation of Plants through Grafting Learners, let us watch the video below on grafting:

(241) What is Grafting? l Artificial Propagation (Animation) - YouTube Fig. 4.5: Diagram showing whip/tongue slanted-grafting Fig. 4.6: Diagram showing Cleft/V-Shaped grafting Aim: To investigate the process of vegetative propagation in plants using the grafting technique and to observe the factors that influence the success of this asexual reproduction method.

Materials needed:

• Two compatible plant species or cultivars (one as the rootstock and one as the scion)

• Sharp, clean grafting knife or razor blade

• Grafting tape or parafilm

• Grafting wax or sealant (optional)

• Potting mix or growing medium

• Pots or containers with drainage holes

• Labels and markers Procedure:

1. Select a healthy, vigorous rootstock plant and a scion (the upper part of the plant to be grafted) from the desired cultivar or species.

2. Prepare the rootstock by making a clean, horizontal cut across the stem, leaving a smooth surface.

3. Prepare the scion by making a clean, sloping cut at the base, creating a wedge-shaped end.

4. Carefully align the cambium layers (the thin, living tissue just under the bark) of the rootstock and scion, ensuring a tight fit.

5. Wrap the graft union securely with grafting tape or parafilm, leaving the tip of the scion exposed.

6. (Optional) Apply a thin layer of grafting wax or sealant over the graft union to protect it.

7. Plant the grafted plant in the potting mix or growing medium, ensuring the graft union is slightly above the soil level.

8. Place the grafted plant in a warm, shaded location and maintain consistent soil moisture.

9. Monitor the graft union regularly for signs of successful union, such as new growth from the scion. Note your findings with regards to:

a. The time taken for the scion (the upper part of the plant being grafted) to start growing and integrate with the rootstock.

b. Differences in the graft union success between various plant species or cultivars that were used in the experiment.

c. Challenges or issues encountered during the grafting process, such as the rejection of the scion or the development of disease problems.

10. After several weeks, gradually expose the plant to more light as the graft union strengthens.

Learners, let us now delve into layering and see how it is operated.

Activity 4.10

Let us watch the video below, discuss the content and perform the activity below.

(241) Science Grade 10 English medium Layering plant propagation - YouTube Fig 4.7: Layering Aim: To investigate the process of vegetative propagation in plants using the layering technique and to observe the factors that influence the success of this asexual reproduction method.

Materials needed:

• Healthy, mature parent plant with flexible, low-growing stems

• Sharp pruners or scissors

• Rooting hormone powder (optional)

• Potting mix or growing medium

• Small pots or containers with drainage holes

• Rocks or pebbles

• Rooting medium (e.g., perlite, vermiculite, or a mixture)

• Wooden or plastic stakes

• Twine or plant ties

• Water spray bottle

• Labels and markers Procedure:

1. Identify a healthy, flexible stem on the parent plant that can be bent down and partially buried in the soil.

2. Prepare the layering site by clearing away any debris or weeds and loosening the soil.

3. Make a shallow wound or cut on the underside of the stem where it will be in contact with the soil.

4. (Optional) Apply rooting hormone powder to the wounded area.

5. Gently bend the stem and bury the wounded portion in the soil, securing it in place with a stake or weight.

6. Cover the buried portion of the stem with a rooting medium, such as a mixture of perlite and potting mix.

7. Water the layered stem gently and keep the soil moist but not waterlogged.

8. Monitor the layered stem for the development of new roots over the next few weeks.

9. Once the new roots have formed, carefully sever the layered stem from the parent plant and transplant it into a separate pot or container.

10. Make and note observations regarding:

a. The rooting success rate of the layered stems.

b. The time taken for the development of new roots on the layered stems.

c. Differences in the rooting and growth patterns between the layered stems that were treated with rooting hormone and those that were not.

d. Variations in the rooting and growth characteristics among different plant species or cultivars that were subjected to the layering process.

e. Challenges or issues encountered during the experiment, such as stem damage or drying out of the layered portion.

Dear learners, the next and last method of artificial propagation for this week is Micropropagation, also known as Tissue Culture.

Activity 4.11

The following videos will help you to understand what micropropagation is.

1. Tissue Culture (youtube.com)

2. (241) Tissue Culture - YouTube The following experiment will be performed in the school laboratory, where possible. If you lack access to the appropriate facilities, you should watch the videos above with more care and summarise the information presented in your own words.

Fig. 4.8: Micropropagation of plants Aim: To investigate the process of vegetative propagation in plants using the tissue culture technique and to observe the factors that influence the success of this asexual reproduction method.

Materials needed:

• Healthy, young plant material (e.g., leaves, stems, or root tips)

• Sterile workspace (e.g., laminar flow cabinet or clean table)

• Sterilised tools (e.g., scalpel, forceps, scissors)

• Culture media (e.g., Murashige and Skoog (MS) medium)

• Plant growth regulators (e.g., auxins, cytokinins)

• Petri dishes or culture vessels with lids

• Autoclave or pressure cooker for sterilising equipment

• Parafilm or plastic wrap for sealing culture vessels

• Incubator or growth chamber with controlled temperature and lighting

• Disinfectants (e.g., bleach, alcohol) for surface sterilisation

• Magnifying glass or stereomicroscope (optional) Procedure:

1. Prepare the work area by thoroughly cleaning and sterilising the surfaces and equipment.

2. Collect the healthy plant material (e.g., young leaves, stem tips, or root tips) from the parent plant.

3. Wash the plant material under running water to remove any dirt or debris.

4. Disinfect the plant material by submerging it in a diluted bleach solution (e.g., 10% bleach) for a few minutes.

5. Rinse the plant material with sterile distilled water several times to remove any traces of the disinfectant.

6. Prepare the culture medium according to the specific protocol, including the necessary plant growth regulators.

7. Aseptically transfer the plant material to the culture vessels containing the prepared medium.

8. Seal the culture vessels with parafilm or plastic wrap to maintain a sterile environment.

9. Place the culture vessels in the incubator or growth chamber with the appropriate temperature and lighting conditions.

10. Monitor the cultures regularly for signs of growth and development, such as callus formation, shoot or root initiation, and plantlet regeneration.

Note your findings.

a. The survival rate of the plant explants (the small specialised plant parts used for tissue culture) in the culture medium.

b. The time taken for the initiation of callus formation, shoot development, or root formation.

c. Differences in the growth and development patterns between the explants cultured on media with varying concentrations of plant growth regulators, such as auxins and cytokinins.

d. Variations in the overall success rate of the tissue culture process among different plant species or cultivars that were subjected to the same experimental conditions.

e. Challenges or issues encountered during the tissue culture propagation, such as contamination of the cultures, browning of the explants, or lack of regeneration of complete plantlets.

11. Carefully transfer the regenerated plantlets to larger vessels or soil for further growth and acclimatisation.

Hello learner, you are about to learn about the mechanism by which humans reproduce. When sexually mature females and males engage in sexual intercourse, it is possible for conception to take place under the right conditions.

To start with you will learn about the female human reproductive system, followed by the male reproductive system to appreciate how the two systems work together to produce offspring.

The female reproductive system is responsible for the production of eggs (ova), the reception of sperm for fertilisation, and the support of embryo development.

It consists of several structures each with unique functions contributing to the reproductive process.

Fig. 4.9: Structure of Female Reproductive System of Humans

Activity 4.12

Look at Figure 4.9 carefully. Suggest the functions of each structure. Copy and complete the table below with your suggested functions of each structure.

Find the solutions in Annex 4.1 to correct and complete your Table 4.4 below.

Table 4.4: The main reproductive structures and their functions in the female reproductive system Description Function Ovaries Oviducts Uterus Cervix Vagina Vulva

Activity 4.13: Drawing and Labelling the Female Reproductive System of Humans.

Materials needed:

• Hb pencil well sharpened

• Eraser

• Sheet of plain A4 paper Procedure:

1. Look at the diagram of the female reproductive system carefully taking into consideration the proportion of the parts forming the system. Re- read your completed table from Activity 1.

2. Put all your notes and diagrams away; you will now replicate them from memory.

3. Using a pencil and paper, make an outline of the female reproductive system proportionately.

4. The outline must be entire, there should be no broken line or woolly outline.

5. If you make a mistake in the outline, use the eraser to clean the mistake and redo that part clearly and smoothly.

6. If it is a vertical/longitudinal section you are drawing, use double lines to show the thickness.

7. Avoid shading of any kind.

8. Label each vital part of the female reproductive system, giving its name and function.

9. Give your drawing an appropriate heading E.g. A Drawing of Longitudinal Section of a Female Reproductive System of Human.

10. Display your drawing for your friends or classmates to see and critique.

Hello learner, you are making progress. Now you are going to learn something about the male reproductive system of humans and appreciate how it compliments the female reproductive system in the reproduction of humans.

Structure of the Male Reproductive System

The male reproductive system is responsible for the production and delivery of sperms which are necessary for the fertilisation of the egg. Hormones such as testosterone play a crucial role in regulating the male reproductive system’s functions.

Fig. 4.10: Vertical Section of Male Reproductive System

Activity 4.14

Look at Figure 4.10 carefully. Suggest the functions of each structure. Copy and complete the table below with your suggested functions of each structure.

Find the solutions in Annex 4.1 to correct and complete your table below.

Table 4.5: The main reproductive structures and their functions in the male reproductive system Description Function Testes Epididymis Vas Deferens Seminal Vesicles, Prostate Gland and Bulbourethral Glands

Activity 4.15: Drawing and Labelling the Male Reproductive System of Humans.

Materials needed:

• Hb pencil well sharpened

• Eraser

• Sheet of plain A4 paper Procedure:

1. Look at the diagram of the male reproductive system carefully taking into consideration the proportion of the parts forming the system. Re- read your completed table from Activity 4.14.

2. Put all your notes and diagrams away; you will now replicate them from memory.

3. Using a pencil and paper, make an outline of the male reproductive system proportionately.

4. The outline must be entire, there should be no broken line or woolly outline.

5. If you make a mistake in the outline, use the eraser to clean the mistake and redo that part clearly and smoothly.

6. If it is a vertical/longitudinal section you are drawing, use double lines to show the thickness.

7. Avoid shading of any kind.

8. Label each vital part of the male reproductive system, giving its name and function.

9. Give your drawing an appropriate heading. For example, a drawing of the longitudinal section of a male reproductive system of humans.

10. Display your drawing for your friends or classmates to see and critique.

Processes of Reproduction in Humans

1. Copulation: Also known as sexual intercourse, copulation involves the insertion of the erect penis into the vagina. During this process, semen is ejaculated into the vagina.

2. Fertilisation: Fertilisation is the fusion of male and female sex cells in the oviduct. This forms a zygote, the single-cell embryo with a complete set of chromosomes from both parents.

3. Implantation: Implantation is the attachment of an embryo to the uterine wall for nourishment. After fertilisation, the zygote undergoes several divisions to form a blastocyst. The blastocyst moves down through the oviduct until it enters the uterus, it then implants itself into the lining of the uterus (endometrium), where it continues to grow and develop.

4. Foetal Development: Following implantation, the blastocyst develops into an embryo, and then into a foetus. During foetal development, organs and systems begin to form and differentiate. This stage spans three trimesters (each three months long), with distinct milestones such as the development of limbs, organs, and the nervous system.

5. Role of the Placenta: The placenta forms from tissues of both the embryo and the mother. It serves as the interface between the maternal and foetal circulatory systems facilitating the exchange of nutrients, oxygen, and waste products. Moreover, toxins such as nicotine and alcohol can cross the placenta from the mother’s bloodstream and damage the foetus. The placenta also produces hormones essential for pregnancy maintenance.

6. Birth: Labour is the process by which a foetus is expelled from the uterus through the birth canal (vagina). It involves uterine contractions coordinated by hormonal signals. After birth, the umbilical cord is typically clamped and cut, separating the newborn from the placenta.

7. Breastfeeding: Breastfeeding is the process of feeding a newborn with breast milk produced by the mother’s mammary glands. Breast milk provides essential nutrients, antibodies, and other factors crucial for the baby’s growth, development, and immune system function. It also fosters bonding between the mother and the infant. In some cases, mothers choose not to or are unable to breastfeed, for a variety of reasons, and in these scenarios, formula derived from cow’s milk is available.

Activity 4.16

Copy the link that follows into a browser and click to view and listen to a video of some processes of human reproduction: https://youtu.be/N66sAZH1VA8 Afterwards, make a schematic diagram or storyboard to show the stages of reproduction in humans.

Activity 4.17

Research some of the primary medical conditions which can adversely affect the function of both male and female sex organs. Create a fact sheet or poster summarising these, as well as giving advice as to how these conditions may be avoided, where possible.

Hello learners. In this lesson, you will discuss menstruation, describe how it occurs and identify hormones responsible for menstruation. You will also look at the significance of the menstrual cycle in sexual reproduction.

Overview of the Menstrual Cycle

The menstrual cycle consists of natural changes that occur in a woman’s body every month, if she is of reproductive age. It involves a series of hormonal, physiological and behavioural changes in the body that prepare it for potential pregnancy.

Menstruation starts at puberty, usually between 8 and 15 years of age. It usually begins two years after breasts and pubic hair start to develop and ends at menopause.

However, the cycle will usually stop while a woman is pregnant.

The menstrual cycle typically lasts around 28 days, although it can vary from woman to woman. This varies between 20 and 40 days and sometimes from cycle to cycle. It is counted from the first day of a period (appearance of vaginal bleeding) to the first day of the next period.

It is important to mention that the cycle is regulated by the complex interplay of hormones which are produced by the ovaries and the pituitary gland.

Significance in Reproduction

The menstrual cycle plays a crucial role in reproduction as it regulates ovulation and the release of an egg from the ovaries. Additionally, the menstrual cycle prepares the uterus for potential pregnancy by thickening its lining. If fertilisation occurs, this lining provides a nourishing environment for the embryo to implant and develop into a baby. If fertilisation does not occur, the lining is shed during menstruation making way for a new cycle to begin.

Activity 4.18

In groups of 2-4, observe the image below and discuss the following:

Fig. 4.11: The 28-day Menstrual Cycle. Image source:

1. In which phase of the cycle do you think pregnancy can occur?

2. Explain your answer.

3. Share your thoughts as part of a whole-class discussion.

Phases of the Menstrual Cycle

In this discussion, you will focus on the phases of the menstrual cycle. Be reminded that, the female reproductive system includes a cycle of events called the menstrual cycle. There are four key phases of the menstrual cycle: the follicular phase, ovulation, the luteal phase, and menstruation. It is tightly controlled by the release and interplay of four main hormones. You will discuss more on hormones later. Discuss the cycle days below.

1. Days 1-5 Menstruation – here, bleeding occurs

2. Days 6-14: Follicular phase – when an egg matures in the ovarian follicle, and the uterine lining prepares to receive a fertilised egg (embryo)

3. Day 14: Ovulation – the ovary releases the egg, which can be fertilised by a man’s sperm if present

4. Days 15-28: Luteal phase – the egg travels through the fallopian tubes (oviducts) to the uterus; if fertilised, the embryo may attach to the uterine lining and the woman will become pregnant; if the egg is not fertilised, the uterine lining will shed, and the cycle will begin again.

Hormones involved in the menstrual cycle Hormones are chemical messengers produced by glands in the endocrine system and released into the bloodstream. They regulate various physiological functions in the body, including growth and development, metabolism, mood, sexual function, and reproduction. Hormones interact with specific target cells or organs, where they exert their effects by binding to hormone receptors.

Hormonal Regulation

Hormone levels are controlled by the pituitary and ovaries. Progesterone and oestrogen are produced in the ovaries whilst Luteinising Hormone (LH) and Follicle Stimulating Hormone (FSH) are produced in the pituitary.

Table 4.6: Hormones associated with the menstrual cycle.

FSH FSH stimulates the growth and development of follicles (fluid- filled sacs) in the ovaries. Within each follicle is an immature egg. FSH is produced in the pituitary.

Oestrogen As the ovarian follicles grow and mature, they produce increasing amounts of oestrogen. Oestrogen plays a key role in thickening the uterine lining (endometrium) in preparation for potential implantation of a fertilised egg.

LH LH surge triggers ovulation, the release of a mature egg from the ovary. LH is also produced in the pituitary.

Progesterone After ovulation, the ruptured follicle transforms into a structure called the corpus luteum which produces and secretes progesterone. Progesterone helps maintain the uterine lining and prepares it for implantation of a fertilised egg. If fertilisation does not occur, the corpus luteum breaks down, leading to a decline in progesterone levels.

Importance of Ovulation

Ovulation is crucial in the menstrual cycle because it marks the release of a mature egg from the ovary, making pregnancy possible. Tracking ovulation is essential for those trying to conceive or avoid pregnancy as it indicates the most fertile window of the cycle; see Annex 4.3 – Further Information for more detail.

Contraception Teenagers who are aware of their menstrual cycle are better equipped to choose suitable contraception methods. Having discussed forms of birth control and their efficacy, it is important to know what contraceptive is consistent and appropriate particularly during the days in the menstrual cycle where conception is most likely to occur. Medical professionals can be engaged to provide advice on contraception.

Contraception refers to methods or techniques used to prevent pregnancy. There are many methods used to prevent pregnancy from hormonal pills, inter-uterine devices, condoms, and hormonal implants. The methods of tracking ovulation (OPKs, cervical mucus monitoring and BBT) can also be used to plan periods of sexual abstinence when fertilisation is most likely. This can be used as a method of contraception though it is unreliable in younger women when periods are unpredictable and vary from month to month.

Activity 4.19

Research and summarise how the following contraception methods work:

Method How it works Hormonal pills Inter-uterine devices (e.g. the hormonal coil / the copper coil) Condoms Cycle tracking Menstrual Disorders Issues affecting a woman’s regular menstrual cycle are referred to as menstrual disorders, these come in a variety of forms. Issues can vary from painful, heavy periods to no periods at all. Menstrual patterns vary widely, but women should be concerned if their periods continue longer than 10 days or if they occur less frequently than 21 days or more. Such occurrences could be a sign of ovulation issues or other illnesses. Some examples of menstrual disorders are given in Annex 4.3.

Reproductive Health Issues

Reproductive health refers to the state of physical, mental, and social well-being in all matters relating to the reproductive system. It encompasses a broad range of issues, including fertility, contraception, sexually transmitted infections (STIs), menstrual health, pregnancy, childbirth, and reproductive cancers. It is crucial to address these issues through education, access to healthcare, and support services to ensure individuals can make informed decisions and maintain their reproductive health.

Menstrual Health

Good menstrual health and hygiene practices can prevent infections, reduce odours, and help stay comfortable during your period. Some menstrual products that can be used to absorb or collect blood during your period, include sanitary pads, tampons, menstrual cups and menstrual discs. The tips in Annex 4.3 can be followed to keep you safe and healthy.

Activity 4.20

As a group, watch these videos and take part in a whole-class discussion surrounding the questions that follow:

1. https://www.youtube.com/watch?v=42WIByexiXc

2. https://www.youtube.com/watch?v=2NjzlvAV1lc

3. https://www.youtube.com/watch?v=Is1LOacgWkc

a. From the videos, how would you describe reproductive health?

b. Identify at least four challenges associated with menstrual health and reproductive health.

c. As either a male or a female, how will you stay healthy during the reproductive stage?

Adolescent Reproductive Health

It is important to discuss among yourselves issues of menstruation cleanliness, fertility awareness, where to find reproductive healthcare services, and normal or abnormal changes during puberty. Sharing thoughts and experiences is the best way to keep everybody safe.

Review Questions 4.1

1. Why is reproduction an essential biological process for the survival and continuation of plant and animal species?

2. How do the different types of plant reproduction, including sexual and various asexual methods, differ in their mechanisms and outcomes?

3. Describe the key stages involved in the sexual reproduction process of flowering plants, from pollination to seed and fruit formation.

4. Design and conduct a hands-on experiment to demonstrate one or more vegetative propagation techniques, such as layering, grafting, or taking cuttings, and explain the practical applications of these asexual reproduction methods.

Review Questions 4.2

1. How will a blocked fallopian tube affect human reproduction?

2. What defect in the male reproductive system can cause the same effect as in question 1?

Review Questions 4.3

1. What are some ways you could cope with menstrual cramps while in school?

2. How should a girl handle talking to a male classmate or teacher about needing to take a break for menstrual reasons?

3. How should one navigate the challenges of exercising or participating in physical activities while menstruating?

4. How can access to reproductive health care contribute to overall health and well-being for individuals and communities?

5. What steps should one take to track and monitor her menstrual cycle, particularly if trying to manage symptoms like irregular periods?

6. Emma is an 18-year-old woman who is in a long-term relationship and wants to prevent unintended pregnancies. She is considering various contraceptive options and is unsure which method would be best for her. She has heard about different types of contraceptives such as the birth control pill, contraceptive implant, and intrauterine device (IUD), but is unsure about the potential side effects and effectiveness of each method. Emma is also concerned about the cost and accessibility of these contraceptive options. Guide her to make an informed decision about which contraceptive method would be most suitable for her lifestyle and health needs.