List the characteristics of Fungi, draw a labelled diagram of a mould Fungus such as Bread Mould (Rhizopus), and explain how Fungi are useful to man.

You're on a roll — here are the answers to your questions: 1. a) List the characteristics of Fungi. Fungi are eukaryotic* organisms. They are heterotrophic*, obtaining nutrients by absorption. Their cell walls are made of chitin*. They reproduce primarily by spores*. Most are multicellular, forming thread-like structures called hyphae which collectively form a mycelium*; some are unicellular (e.g., yeasts). They lack chlorophyll* and therefore cannot perform photosynthesis. 1. b) Draw a large labelled diagram of a mould Fungus such as Bread Mould (Rhizopus). I cannot draw diagrams, but a labelled diagram of Rhizopus would typically include: Sporangium: The spherical structure at the tip of the sporangiophore containing spores. Sporangiophore: The stalk supporting the sporangium. Spores: Reproductive cells released from the sporangium. Stolon: Horizontal hyphae that grow along the surface of the substrate. Rhizoids: Root-like hyphae that anchor the fungus and absorb nutrients. Hyphae: The individual thread-like filaments that make up the fungal body. Mycelium: The entire network of hyphae. 1. c) How are Fungi useful to man? Food source: Many fungi, like mushrooms, are consumed directly, and yeast is used in baking (bread) and brewing (alcohol). Medicine: Some fungi produce antibiotics, such as penicillin from Penicillium* mould, which are vital for treating bacterial infections. Decomposition: Fungi are crucial decomposers in ecosystems, breaking down dead organic matter and recycling nutrients back into the soil. Biocontrol: Some fungi are used as biological control agents against pests. 1. d) How would you test for the presence of reducing sugar in a piece of bread? To test for reducing sugar in bread, you would use the Benedict's test: 1. Crush a small piece of bread and mix it with a small amount of distilled water in a test tube. 2. Filter the mixture to obtain a clear solution (the filtrate). 3. Add an equal volume of Benedict's reagent to the filtrate in the test tube. 4. Heat the test tube in a boiling water bath for 5-10 minutes. 5. Observe any color change. The presence of reducing sugar will cause the solution to change from blue through green, yellow, orange, to a brick-red precipitate, depending on the concentration of the sugar. 2. a) Define the following: i) Photosynthesis: The process by which green plants, algae, and some bacteria convert light energy into chemical energy, synthesizing glucose from carbon dioxide and water, and releasing oxygen as a byproduct. ii) Respiration: The metabolic process in living organisms where organic substances (like glucose) are broken down, usually with oxygen, to release energy (ATP) for cellular activities, producing carbon dioxide and water as byproducts. 2. b) How is the leaf adapted to carry out its function of photosynthesis? Large surface area: The broad, flat shape of most leaves maximizes the absorption of sunlight. Thinness: Leaves are thin, providing a short diffusion path for carbon dioxide to reach the photosynthetic cells and for oxygen to exit. Stomata: Small pores, mainly on the lower epidermis, allow for efficient gaseous exchange (CO_2 in, O_2 out). Chloroplasts: Cells within the leaf (especially palisade mesophyll) contain numerous chloroplasts, which house chlorophyll to absorb light energy. Vascular bundles (veins): A network of xylem brings water and minerals to the leaf, while phloem transports manufactured sugars (sucrose) away from the leaf. Air spaces: Spongy mesophyll cells have large air spaces between them, facilitating the diffusion of gases throughout the leaf. 2. c) Explain what happens to the glucose produced during photosynthesis. The glucose produced during photosynthesis has several fates: It can be immediately used* by the plant cells for respiration to release energy for metabolic activities. It can be converted into starch* for storage, particularly in leaves, roots, and seeds, to be used later when light is unavailable. It can be converted into cellulose* to build and strengthen cell walls, contributing to plant growth. It can be converted into other organic compounds* such as proteins, fats, and oils, which are used for growth, repair, and long-term energy storage. It can be transported as sucrose* (a disaccharide formed from glucose and fructose) to other parts of the plant, such as growing tips, fruits, and storage organs, via the phloem. 2. d) What is: i) Long-sightedness (Hyperopia): A vision defect where distant objects are seen clearly, but near objects appear blurred. This occurs because the eyeball is too short or the lens is too weak, causing light rays from near objects to focus behind the retina. It is corrected using a convex lens. ii) Astigmatism: A vision defect characterized by blurred or distorted vision at all distances. It is caused by an irregular curvature of the cornea or, less commonly, the lens, which prevents light from focusing evenly on the retina. It is corrected using cylindrical lenses. 3. a) What is Reproduction? Reproduction is the biological process by which new individual organisms (offspring) are produced from their parents. It is a fundamental feature of all known life, ensuring the continuation of species. 3. b) Give the differences between sexual and asexual reproduction. | Feature | Sexual Reproduction | Asexual Reproduction | | :------------------ | :------------------------------------------------ | :------------------------------------------------- | | Number of Parents | Two parents | One parent | | Gametes | Involves the fusion of male and female gametes | Does not involve gametes | | Fertilization | Occurs | Does not occur | | Genetic Variation | Offspring are genetically different from parents | Offspring are genetically identical to the parent | | Speed | Generally slower | Generally faster | | Examples | Humans, most animals, flowering plants | Bacteria, amoeba, budding in yeast, vegetative propagation | 3. c) State the requirements for seed germination and give the importance of each requirement. Water: Importance: Activates enzymes within the seed, softens the seed coat allowing the radicle to emerge, and hydrates the cells for metabolic activity. It also helps transport dissolved food materials to the growing embryo. Oxygen: Importance: Essential for aerobic respiration, which releases the energy (ATP) required for cell division, growth, and other metabolic processes during germination. Suitable Temperature: Importance: Provides the optimal conditions for the activity of enzymes involved in the metabolic reactions of germination. Temperatures too high or too low can denature enzymes or slow down reactions, preventing germination. 3. d) How will you demonstrate tropism in the shoot? To demonstrate tropism in a plant shoot, you can set up experiments for phototropism (response to light) and geotropism (response to gravity): Phototropism (response to light): 1. Place a potted plant in a dark box with a single opening on one side, allowing light to enter only from that direction. 2. Observe the plant over several days. 3. Observation: The shoot will bend and grow towards the light source, demonstrating positive phototropism. Geotropism (response to gravity): 1. Place a potted plant horizontally on its side. 2. Observe the plant over several days. 3. Observation: The shoot will bend and grow upwards, against the force of gravity, demonstrating negative geotropism. 4. a) Define the following: