Life Sciences Grade 11 Revision Term 1 Part 1

The diagram below represents the structure of a Bacteriophage.

Identify the following parts:
(a) A
(b) B
(c) C
(d) D

Based on the common structure of a bacteriophage, the labeled parts can be identified as follows:

(a) A – Protein Shield → This refers to the capsid, which is the protective outer shell made of proteins that encloses the viral genetic material.

(b) B – DNA → This is the genetic material contained within the head of the bacteriophage. It carries the instructions for replication when the virus infects a host cell.

(c) C – Collar → This is a small structure located between the head (capsid) and the tail. It helps provide stability to the bacteriophage

e) E – Fibre → These are the tail fibers, which help the bacteriophage attach to the surface of a bacterial host cell. They recognize and bind to specific receptors on the bacterial cell wall, allowing the virus to initiate infection.

(f) F – Base Plate → This is the base plate, a crucial structure at the bottom of the tail. It plays a key role in anchoring the virus to the host cell and initiating the injection of viral DNA into the bacterium.

Question

Why are viruses referred to as being acellular?

viruses are referred to as being acellular, because they do not have a cell structure. They lack a nucleus, cytoplasm, or organelles and consist only of genetic material (DNA or RNA) enclosed in a protein coat, making them non-cellular entities.

Question

State ONE characteristic of viruses that qualifies them as:

i. Living things – Viruses are considered to be living things because they can reproduce, but only inside a host cell. They also die when their host is destroyed or when exposed to unfavorable conditions.

ii. Non-living things – Viruses qualify as non-living things as they do not feed or respire because they lack cellular structures such as organelles and enzymes needed for metabolism.

Give the correct biological term for each of the following descriptions

Question: The gut that runs through an organism with two openings is called a………

The correct answer is A through gut which refers to a digestive system that has two openings: a mouth at one end and an anus at the other. This type of digestive system allows for a one-way flow of food through the body.

Question: The tree that shows evolutionary relationships among different species is called a………

The correct answer is phylogenetic tree. A phylogenetic tree is a diagram that represents how species have evolved from common ancestors over time. It shows branches, where closely related species are grouped together, helping scientists understand evolutionary connections.

Question: A group of plants that have seeds enclosed in an ovary are known as………

The correct answer is angiosperms. Angiosperms are flowering plants where the seeds develop inside a fruit or ovary. This protective structure helps in seed dispersal and provides an advantage over gymnosperms, which have exposed seeds.

Question: The concentration of sense organs at the anterior end of an animal leading to the formation of a head is called………

The correct answer is cephalization. Cephalization is the development of a distinct head region where sensory structures, such as eyes and a brain, are concentrated. This adaptation is common in bilaterally symmetrical animals and helps improve movement and environmental awareness.

Question: The cell walls of most fungi are mainly composed of………

The correct answer is chitin. Fungal cell walls contain chitin, a tough and flexible structural component. Unlike plants, which have cellulose-based cell walls, fungi rely on chitin for protection and structural support.

Question: Viruses are referred to as being acellular because they………

The correct answer is do not have a cell structure. Viruses lack a nucleus, cytoplasm, and organelles, consisting only of genetic material (DNA or RNA) enclosed in a protein coat. This makes them non-cellular entities that depend on a host cell for replication.

Question: One characteristic of viruses that qualifies them as living things is………

The correct answer is they reproduce/die. Viruses can replicate, but only inside a host cell. They can also be destroyed when their host is eliminated or when exposed to unfavorable conditions.

Question: One characteristic of viruses that qualifies them as non-living things is……… The correct answer is they do not feed or respire. Unlike living organisms, viruses lack cellular machinery for metabolism and energy production, making them inactive outside a host.

Question: Phylum of all animals with a vertebral column in adults
The correct answer is Chordata. The phylum Chordata includes all animals that possess a vertebral column (backbone) at some stage in their life cycle. This group includes fish, amphibians, reptiles, birds, and mammals.

Question: Transfer of pollen from an anther to the stigma
The correct answer is Pollination. Pollination is the process by which pollen grains are transferred from the anther (male reproductive part) to the stigma (female reproductive part) of a flower, enabling fertilization to occur.

Question: The type of reproduction in plants that produces offspring with identical genetic composition
The correct answer is Asexual reproduction. Asexual reproduction occurs when plants produce offspring without the involvement of gametes (sperm and egg cells). Since no genetic mixing occurs, the offspring are genetically identical clones of the parent plant. Examples include budding, runners, and vegetative propagation.

Study the diagram below showing the arrangement of body tissues.

Question: The type of symmetry shown in the diagram above is called___________.
The correct answer is bilateral symmetry. This type of symmetry means that the body can be divided into two equal halves along a single plane, with one mirror-image side on either side of the central axis. This is typical of many animals, including humans.

Question: Explain ONE advantage of the symmetry mentioned in QUESTION ABOVE
The correct answer is bilateral symmetry allows for cephalization. This means that the concentration of sensory organs and nervous tissue is located at the front of the organism, forming a distinct head. The advantage of cephalization is that it enhances the animal’s ability to detect prey and danger more effectively, making it easier to interact with its environment.

Question: Identify the type of skeleton of the organism shown in the diagram above.
The correct answer is exoskeleton. An exoskeleton is a hard external structure that provides support and protection to the organism. It is commonly found in arthropods, such as insects and crustaceans.

Question: State TWO disadvantages of the type of skeleton mentioned in QUESTION 1.4.3.
The correct answer is:

1. Exoskeleton restricts animal growth. Since the exoskeleton is rigid and does not grow with the animal, the organism needs to shed it periodically, which can be limiting for its growth.
2. Exoskeleton requires moulting, which makes the animal vulnerable. During the process of shedding or moulting its exoskeleton, the animal is exposed and more susceptible to predators.

The diagram below shows the branch of the pine tree.

Question: Name the agent of pollination for the above flower.

The correct answer is wind. Wind-pollinated flowers depend on air currents to transfer pollen from one flower to another. Unlike insect- or animal-pollinated flowers, they do not require external pollinators such as bees, butterflies, or birds. Instead, they produce and release large amounts of lightweight pollen into the air, increasing the likelihood of successful pollination.

Question: List the characteristics of the flower that make it adapted for the agent mentioned in the question above.

The correct answers are:

• Wind-pollinated flowers produce light, smooth, and dry pollen grains, which allow them to be easily carried by the wind over long distances. Since wind pollination is a random process, having lightweight pollen increases the chances of successful fertilization by ensuring that a sufficient amount of pollen reaches other flowers of the same species.
• The anthers of wind-pollinated flowers are loosely attached to their filaments, making them highly flexible. This flexibility enables them to sway with even the slightest breeze, which helps in the efficient release of pollen into the air. The movement ensures that a large quantity of pollen is dispersed, increasing the likelihood of pollination.
• To capture airborne pollen effectively, wind-pollinated flowers have a large, feathery, and sticky stigma. This adaptation increases the surface area of the stigma, making it easier to trap pollen as it is carried by the wind. The sticky texture ensures that the pollen remains on the stigma, allowing fertilization to take place.
• Unlike insect-pollinated flowers, wind-pollinated flowers do not produce a scent or nectar. Since they do not rely on attracting pollinators, these flowers save energy by not producing sweet-smelling fragrances or nectar rewards. Instead, they rely entirely on wind currents to transfer pollen.
• Wind-pollinated flowers typically lack brightly colored petals, as they do not need to attract insects or animals. Their dull or pale-colored petals help reduce energy expenditure, focusing their resources on pollen production and dispersal instead. This adaptation ensures that they can successfully reproduce without relying on external pollinators.

Wind pollination is a less targeted process than insect pollination, so these adaptations help ensure that as much pollen as possible reaches another flower of the same species.

Question: Name the advantage of asexual reproduction in plants.

The correct answer is:

• Rapid Production of Offspring: Asexual reproduction allows plants to produce a large number of offspring in a short period. This quick reproduction leads to rapid population growth, which is particularly useful when conditions are favorable and resources are abundant. The ability to rapidly spread and colonize an area increases the plant’s chances of survival in competitive environments.
• Genetically Identical Offspring: Offspring produced through asexual reproduction are genetically identical to the parent plant. This means that if the parent is well-adapted to its environment, the new plants will also possess the same traits, making them equally suited for survival in that environment. This can be beneficial in stable habitats where the parent’s traits are favorable for survival.
• Speed of Reproduction: Asexual reproduction does not require fertilization or seed formation, enabling plants to reproduce more quickly. This faster reproduction cycle means plants can produce new individuals without waiting for pollination, making it a highly efficient way of ensuring the survival and expansion of the species.
• Independence from Pollinators and Seed Dispersal: Asexual reproduction does not depend on pollinators or seed dispersal mechanisms, which can be unreliable or limited in certain environments. In stable conditions where the parent plant is already well-suited to the habitat, this form of reproduction provides a dependable way for plants to reproduce without relying on external factors like insects or wind.

Question: Explain why seedless vascular plants are able to grow taller than non-vascular plants.

The correct answer is:

• Presence of Xylem and Phloem: Seedless vascular plants, like ferns, have specialized conducting tissues known as xylem and phloem. These tissues are crucial for transporting water, nutrients, and sugars throughout the plant, allowing them to grow taller than non-vascular plants. The ability to move these substances efficiently enables vascular plants to support more extensive growth.
• Water and Mineral Transport by Xylem: The xylem is responsible for transporting water and minerals from the roots to the rest of the plant. This system helps vascular plants maintain hydration and structural support, which is essential for taller growth. Without xylem, the plant would struggle to carry water to higher parts of the plant, limiting its height.
• Nutrient and Sugar Distribution by Phloem: The phloem distributes nutrients and sugars produced by the plant to various parts, ensuring that the entire plant receives the energy it needs for growth. This efficient distribution system allows vascular plants to fuel their taller structures, while non-vascular plants, which lack phloem, cannot support such growth.
• Efficient Transport Systems for Greater Height: With both xylem and phloem, seedless vascular plants can grow taller than non-vascular plants. Non-vascular plants depend on simple diffusion to move water and nutrients, which limits their size and restricts them to lower-growing forms. Vascular plants, on the other hand, can support taller growth because they have evolved these efficient internal transport systems.

Question: Give the adaptations of angiosperms that help them survive on land.

The correct answers are:

• Waxy Cuticle on Leaves: Angiosperms have leaves with a waxy cuticle, which acts as a protective layer. This cuticle helps to prevent excessive water loss due to evaporation, allowing the plant to conserve water and survive in land-based environments, where water can be more scarce.
• True Roots, Stems, and Leaves: Angiosperms have true roots, stems, and leaves, which allow them to efficiently absorb water and nutrients from the soil. The roots anchor the plant securely, while the stem supports the plant upright, and the leaves carry out photosynthesis, all of which help the plant thrive on land.
• Enclosed Embryo within a Seed: The embryo in angiosperms is enclosed within a seed, providing it with protection from harsh environmental conditions. This structure prevents the embryo from drying out before germination, increasing the likelihood of successful reproduction in terrestrial environments.
• Vascular Tissues (Xylem and Phloem): Angiosperms possess vascular tissues like xylem and phloem, which are crucial for the transport of water, minerals, and nutrients throughout the plant. These tissues allow angiosperms to grow taller, transport resources efficiently, and thrive in a variety of land environments.

Read and Answer the Questions below

Malaria is responsible for over 400,000 deaths worldwide each year.

Question: Name the protozoan that causes malaria.

The correct answer is: Plasmodium is the protozoan responsible for causing malaria. This parasite enters the human bloodstream through the bite of an infected mosquito and multiplies in the liver before attacking red blood cells.

Question: Name the vector that spreads malaria.

The correct answer is: The Anopheles mosquito is the vector that spreads malaria. It transmits the Plasmodium parasite when it bites a human, injecting the parasite into the bloodstream.

Question: List the symptoms experienced by people with malaria.

The correct answers are:

• Fever and chills are common symptoms as the parasite infects and destroys red blood cells, leading to cycles of high fever and sweating.

• Headache, nausea, and vomiting may also occur as the body’s immune system responds to the infection, causing general discomfort and dehydration.

Question: Explain why malaria is only found in certain regions of Africa.

The correct answer is: Malaria is prevalent in certain regions of Africa because many African countries experience high temperatures and humid conditions, which create the perfect environment for the Anopheles mosquito to thrive and multiply. The warm climate allows the parasite to develop within the mosquito, increasing the chances of transmission to humans.

Grade 11 learners conducted an experiment to Determine the Optimum Temperature for Growth of Bread Mould

Procedure:

• Four plastic containers with lids were used for the investigation.
• Each container was labeled A, B, C, and D.
• A slice of bread was placed inside each container.
• 20ml of water was sprinkled over each slice of bread.
• The containers were placed in different environments:
  • Container A: Stored in a fridge.
  • Container B: Kept in a cupboard.
  • Container C: Left at room temperature.
  • Container D: Placed on a window sill.
• The containers were left undisturbed in their respective conditions for one week.
• After a week, the bread slices were removed and placed next to each other for comparison.
• The learners repeated the investigation twice to ensure reliability.

Results of the Investigation (Table 3.1):

Question: Identify the (a) dependent variable and (b) independent variable in this investigation.

The correct answer is:

(a) The dependent variable in this investigation is the growth of bread mould. This is the variable being measured, as the learners are observing how much mould develops under different conditions. The results are recorded as a percentage to show how much the bread was affected by mould growth over the course of a week.

(b) The independent variable is temperature. Each container was placed in a different environment with varying temperatures, such as inside a fridge, a cupboard, at room temperature, and on a window sill. The purpose of the investigation was to determine how temperature influences the growth of bread mould.

Question: What did the learners do to improve the reliability of their investigation?

The correct answer is:

The learners repeated the investigation to improve its reliability. Repeating an experiment ensures that the results are consistent and not just due to chance. By conducting the investigation multiple times, the learners could confirm that the mould growth patterns observed were accurate and not influenced by random external factors. This increases the credibility of their findings.

Question: Identify one factor that was kept constant during the investigation.

The correct answer is:

One constant variable in the investigation was the amount of water sprinkled on each slice of bread, which was 20 ml. Keeping this factor the same ensured that any differences in mould growth were due to temperature rather than varying moisture levels. If the amount of water had been different for each slice, it could have affected the results, making it unclear whether temperature or water availability was responsible for the differences in mould growth.

Complete the table below by comparing the characteristics of the four plant groups. Only write the question number and the corresponding answer in the provided spaces.

3.2.1: Gymnosperm
Gymnosperms are seed-producing plants that do not enclose their seeds within a fruit. Instead, their seeds are exposed on the surface of cones or other structures. This group includes conifers like pine trees and firs.

3.2.2: No true stems, leaves, and roots (thallus)
Bryophytes, such as mosses and liverworts, lack true vascular tissues and do not have differentiated stems, leaves, and roots. Their body is a simple, undifferentiated structure called a thallus. These plants are typically small and grow in moist environments.

3.2.3: TRUE stems, leaves, and roots
Pteridophytes, including ferns, have a well-differentiated plant body with true stems, leaves, and roots. They possess vascular tissues, allowing for efficient transport of water and nutrients. These plants are typically found in moist environments.

3.2.4: No seeds
Bryophytes do not produce seeds. They reproduce via spores and require water for fertilization. This dependence on water limits their distribution to moist habitats.

3.2.5: Seed enclosed in a fruit
Angiosperms, or flowering plants, produce seeds that are enclosed within a fruit. The fruit develops from the ovary of the flower and aids in seed dispersal. This group includes a vast diversity of plants, from grasses to trees.

3.2.6: Does not depend on water for fertilization of gametes
Angiosperms do not require water for fertilization. They utilize various mechanisms, such as wind and animal pollination, to transfer pollen from one flower to another, facilitating fertilization without the need for water

Coronavirus, the world’s greatest enemy.

Question: State TWO recommendations to prevent the spread of coronavirus.

The correct answer is:

• Regular hand washing. Regular hand washing helps reduce the transmission of the virus by removing virus particles from the hands, especially after touching potentially contaminated surfaces.
• Covering mouth and nose when coughing and sneezing. This ensures that respiratory droplets containing the virus are contained, preventing it from spreading to others.
• Maintain social distancing. This reduces the risk of the virus spreading from person to person, especially in public spaces, by maintaining a physical distance to prevent respiratory droplets from being shared.

Question: Give ONE reason why it is difficult to develop a cure for viral diseases.

The correct answer is:

• Viruses are non-living. Since viruses are non-living entities, they cannot be targeted in the same way as living organisms. They need host cells to replicate, and this makes it difficult to create a cure that kills the virus without harming healthy cells.

Question: Explain the effect of coronavirus suppressing the immune system in people with underlying conditions/diseases.

The correct answer is:

• They have weakened immune systems. Individuals with underlying conditions often have a weakened immune system, which means their bodies are less capable of fighting infections. When the coronavirus suppresses their immune system further, they become more vulnerable to severe complications and infections.
• They are vulnerable to any form of infections. With a weakened immune system, individuals are more susceptible to all types of infections, not just the coronavirus, making it harder for them to recover from illnesses.
• Their bodies are not able to fight them. Due to a compromised immune system, the body’s ability to mount an effective immune response is reduced, making it harder for these individuals to fight off infections, including the coronavirus.

Question: State ONE significance of vaccines in the human body.

The correct answer is:

• They stimulate the immune system to produce antibodies. Vaccines trigger the immune system to recognize and prepare antibodies against specific pathogens, ensuring that if the body is exposed to the pathogen in the future, it can respond more quickly and effectively.

The diagram below shows one of the phyla you studied.

Question: Identify the kingdom to which the above organism belongs.

The organism belongs to the Kingdom Fungi. Members of the Fungi kingdom are eukaryotic organisms that function primarily as decomposers in ecosystems. Fungi obtain nutrients through extracellular digestion, releasing enzymes to break down organic matter before absorbing the nutrients. They typically grow as thread-like structures called hyphae, which interconnect to form a network known as mycelium. This characteristic makes fungi effective in decomposing organic material and recycling nutrients in ecosystems.

Question: Give the letter and name of the part that:

A, Anchors the fungus to the substrate:
The Correct answer is D: Rhizoids.
Rhizoids are root-like structures that anchor the fungus to its substrate, helping it stay in place. They also assist in the absorption of nutrients from decomposing organic matter. These structures are crucial for fungi like molds, which rely on rhizoids to attach to surfaces and gather nutrients.

B, Provides a branched horizontal covering on the substrate:
The Correct answer is C: Stolon.
Stolons are horizontal hyphae that spread across the surface of the substrate. They help the fungus expand and colonize new areas. This horizontal growth is important for the fungus as it allows it to cover more ground and find more resources, contributing to the spread of the mycelium network.

C, Produces mature spores:
The Correct answer is A: Sporangium.
The sporangium is a structure responsible for producing and releasing spores in certain types of fungi, such as those in the Zygomycota group. These spores allow the fungus to reproduce and spread. While other fungi may produce spores in different structures (such as conidia in Ascomycota or basidia in Basidiomycota), the sporangium is specific to some fungi, particularly those that reproduce via spore formation in this structure.

The diagram Below represents a flower.

Question: Name the agent of pollination for the above flower.

The agent of pollination for this flower is wind. Wind-pollinated flowers rely on air currents to carry pollen from one flower to another. Unlike flowers pollinated by insects, birds, or other animals, wind-pollinated flowers do not attract pollinators with bright colors, nectar, or scent. Instead, they produce large amounts of lightweight pollen, which is easily carried by the wind, to increase the chances of successful pollination.

Question: List the characteristics of the flower that make it adapted for the agent mentioned in the question above.

1, Wind-pollinated flowers produce light, smooth, and dry pollen grains, which makes it easier for the wind to carry them over long distances. Since wind pollination is a random process, these flowers produce large amounts of pollen to increase the chances of successful fertilization. The lightweight and dry nature of the pollen prevents it from clumping together, allowing it to be dispersed more efficiently by air currents.

2, Wind-pollinated flowers have a large, feathery, and sticky stigma, which is specially adapted to capture airborne pollen. The feathery structure provides a greater surface area, making it more effective in trapping pollen grains as they pass through the air. Additionally, the sticky surface helps the pollen adhere to the stigma, ensuring that fertilization can take place once the pollen reaches the flower.

3, Wind-pollinated flowers have loosely attached and flexible anthers, which allow them to move freely with the slightest breeze. This movement helps release large amounts of pollen into the air, increasing the chances that some of it will reach other flowers of the same species. By being positioned outside the flower, the anthers are exposed to the wind, making pollen dispersal more effective.

Question: Name the advantage of asexual reproduction in plants.

1, One major advantage of asexual reproduction in plants is the ability to produce offspring rapidly. This allows plants to multiply quickly, especially when conditions such as water, nutrients, and sunlight are favorable. By reproducing at a fast rate, plants can spread efficiently and dominate their environment, increasing their chances of survival.

2, Another key benefit of asexual reproduction in plants is that the offspring are genetically identical to the parent. Since there is no genetic variation, all new plants inherit the same traits as the parent. If the parent is well-adapted to its surroundings, the offspring will also thrive under the same environmental conditions, ensuring the species’ continued success.

3, Asexual reproduction in plants also offers the advantage of a faster reproduction cycle. Unlike sexual reproduction, which requires pollination, fertilization, and seed development, asexual reproduction eliminates these steps. This means new plants can grow directly from the parent, allowing for quicker expansion of the population.

4, Additionally, asexual reproduction in plants does not depend on external factors like pollinators or seed dispersal. In environments where pollinators such as bees, birds, or the wind are limited, sexual reproduction may not be reliable. Asexual reproduction ensures that plants can continue to reproduce successfully without relying on outside agents, making it an effective strategy for survival in challenging or isolated environments.

Question:
Explain why seedless vascular plants are able to grow taller than non-vascular plants.

1, Seedless vascular plants can grow taller than non-vascular plants because they possess xylem and phloem. These specialized vascular tissues transport water, minerals, and nutrients throughout the plant. With an efficient internal transport system, seedless vascular plants, such as ferns, can support larger structures and grow much taller than non-vascular plants, which lack these tissues.

2, The presence of xylem allows seedless vascular plants to transport water and minerals from the roots to the rest of the plant. Xylem plays a crucial role in maintaining hydration and providing structural support. This upward movement of water ensures that taller plants can receive the moisture they need to survive. In contrast, non-vascular plants rely on simple diffusion, which limits their ability to transport water over long distances, restricting their height.

3, Phloem enables the distribution of nutrients and sugars throughout the plant, supporting its growth. Phloem carries sugars produced during photosynthesis from the leaves to other parts of the plant, ensuring that all tissues receive the necessary energy for development. Without this efficient distribution system, plants would struggle to grow beyond a certain height. Non-vascular plants lack phloem, making it difficult for them to sustain larger structures.

4, The internal transport system in seedless vascular plants allows them to grow taller and stronger compared to non-vascular plants. Non-vascular plants, such as mosses and liverworts, rely on direct absorption and diffusion of water and nutrients, which limits their size. In contrast, vascular plants have evolved xylem and phloem, enabling them to grow upright, reach sunlight more effectively, and spread over larger areas.

Question:
Give the adaptations of angiosperms that help them survive on land.

1, One adaptation that helps angiosperms survive on land is the presence of a waxy cuticle on their leaves. This cuticle acts as a protective layer that prevents excessive water loss due to evaporation. Since water can be scarce on land, this adaptation allows angiosperms to conserve moisture and survive in drier environments.

2, Another key adaptation of angiosperms is the presence of true roots, stems, and leaves. Roots anchor the plant in the soil and absorb water and nutrients, while stems provide support and transport materials throughout the plant. Leaves carry out photosynthesis, converting sunlight into energy for growth. These structures enable angiosperms to efficiently obtain resources and thrive in terrestrial habitats.

3, The enclosed embryo within a seed provides protection and enhances survival on land. Seeds shield the developing embryo from harsh environmental conditions such as drought, extreme temperatures, and predators. The protective seed coat prevents the embryo from drying out before germination, increasing the chances of successful reproduction in land-based ecosystems.

4, Angiosperms also have vascular tissues (xylem and phloem) that support their survival and growth. Xylem transports water and minerals from the roots to other parts of the plant, while phloem distributes sugars and nutrients where needed. This vascular system allows angiosperms to grow tall, transport essential resources efficiently, and adapt to various terrestrial environments

Read and Answer the Questions Below
Malaria is a life-threatening disease responsible for over 400,000 deaths worldwide each year.

Question: Name the protozoan that causes malaria.

The correct answer is Plasmodium. This is the protozoan parasite responsible for causing malaria. When an infected Anopheles mosquito bites a person, it injects Plasmodium parasites into the bloodstream. These parasites first travel to the liver, where they multiply before attacking and destroying red blood cells, leading to the symptoms of malaria.

Question: Name the vector that spreads malaria.

The correct answer is Anopheles mosquito. This mosquito is the vector, meaning it carries and transmits the malaria-causing Plasmodium parasite from one person to another. When an infected mosquito bites a human, it transfers the parasite into the bloodstream, spreading the disease.

Question: List the symptoms experienced by people with malaria.

People infected with malaria experience several symptoms, including:

1, Fever and chills – These are the most common symptoms. The parasite infects and destroys red blood cells, causing repeated episodes of high fever, sweating, and chills.

2, Headache, nausea, and vomiting – As the immune system fights the infection, the body reacts by triggering headaches, nausea, and vomiting, which can lead to dehydration and general weakness.

Question: Explain why malaria is only found in certain regions of Africa.

Malaria is common in certain parts of Africa because of the warm and humid climate, which provides the perfect breeding conditions for the Anopheles mosquito. High temperatures allow the Plasmodium parasite to develop inside the mosquito, making it more likely to be transmitted to humans. Regions with stagnant water sources, such as lakes, ponds, and swamps, also support the breeding of these mosquitoes, increasing the spread of malaria.

Grade 11 learners conducted an experiment to Determine the Optimum Temperature for Growth of Bread Mould. The following procedure was undertaken.

Four labeled plastic containers (A, B, C, and D) were used.
A slice of bread was placed in each container and sprinkled with 20ml of water.
The containers were stored in different conditions as listed below
A: Fridge.
B: Cupboard.
C: Room temperature.
D: Window sill.
After one week, the bread slices were removed and compared for mould growth. The experiment was repeated twice for reliability.

The Results.
After one week, the highest mould growth (75%) was observed on the bread placed on the window sill, followed by room temperature (50%) and the cupboard (25%). The least mould growth (5%) occurred in the fridge.

Question: Identify the

(a) dependent variable. Dependent Variable:
The growth of bread mould is the dependent variable. A dependent variable is the factor that is measured or observed in an experiment to determine how it is affected by changes in the independent variable. In this investigation, the amount of mould growth on the bread slices was recorded as a percentage after one week. Since the mould growth depended on the temperature conditions in which the bread was placed, it is classified as the dependent variable.

(b) Identify the independent variable. The temperature is the independent variable. An independent variable is the factor that is deliberately changed or controlled in an experiment to observe its effect on the dependent variable. In this case, the bread slices were placed in different environments with varying temperatures—inside a fridge, in a cupboard, at room temperature, and on a window sill. The purpose of the investigation was to examine how these temperature differences influenced the growth of bread mould, making temperature the independent variable.

Question: What did the learners do to improve the reliability of their investigation?

The learners repeated the investigation to improve its reliability. Repeating an experiment ensures that the results are consistent and not just due to chance. By conducting the investigation multiple times, the learners could confirm that the mould growth patterns observed were accurate and not influenced by random external factors. This increases the credibility of their findings.

Question: Identify one factor that was kept constant during the investigation.

One constant variable in the investigation was the amount of water sprinkled on each slice of bread, which was 20 ml. Keeping this factor the same ensured that any differences in mould growth were due to temperature rather than varying moisture levels. If the amount of water had been different for each slice, it could have affected the results, making it unclear whether temperature or water availability was responsible for the differences in mould growth.

Coronavirus: The World’s Greatest Enemy
Question: State two recommendations to prevent the spread of coronavirus. The following recommendations can be used to prevent the spread of corona virus
1, Regular hand washing. Washing hands frequently with soap and water helps remove virus particles, preventing the spread of the virus, especially after touching contaminated surfaces. Proper hand hygiene significantly reduces the risk of infection.

2, Covering the mouth and nose when coughing or sneezing. This prevents respiratory droplets containing the virus from being released into the air, reducing the chances of infecting others. Using a tissue or the elbow to cover coughs and sneezes is an effective measure.

3, Maintaining social distancing. Keeping a safe distance from others, particularly in public spaces, minimizes the risk of inhaling respiratory droplets carrying the virus, thus reducing person-to-person transmission.

Question: Give one reason why it is difficult to develop a cure for viral diseases.

Viruses are non-living and rely on host cells to replicate. Unlike bacteria, which can be killed with antibiotics, viruses cannot be destroyed in the same way. Developing a cure is challenging because antiviral treatments must target the virus without damaging healthy human cells, making treatment complex and difficult.
Question: Explain the effect of coronavirus suppressing the immune system in people with underlying conditions/diseases.

1, Overloads the already weakened immune system. People with underlying health conditions, such as diabetes, heart disease, or respiratory illnesses, often have an immune system that is not functioning at full strength. When coronavirus attacks the body, their weakened immune system struggles to mount an effective defense, making them more susceptible to severe illness.

2, Higher risk of infections. Since their immune system is already compromised, these individuals are not only more vulnerable to severe COVID-19 symptoms but also at greater risk of developing secondary infections, such as bacterial pneumonia or other viral illnesses, further worsening their health.

3, Reduced ability to recover. A weakened immune system means the body takes longer to fight off infections. As a result, people with pre-existing conditions are more likely to experience prolonged illness, severe complications, organ damage, or even death due to their body’s inability to fully eliminate the virus.

Question: State one significance of vaccines in the human body.

They stimulate the immune system to produce antibodies. Vaccines trigger the immune system to recognize and prepare antibodies against specific pathogens, ensuring that if the body is exposed to the pathogen in the future, it can respond more quickly and effectively. This process helps protect the body from infections by “training” the immune system to recognize and neutralize harmful invaders before they can cause serious illness.