9. (a) Give the differences between the following items as used in growth by giving examples.
(i) Diffuse growth and allometric growth
(ii) Limited growth and unlimited growth
(b) (i) Draw the diagram of sigmoid growth curve, label the four significant phases.
(ii). Briefly explain why during adolescence stage the rate of growth is rapid
10. Many people believe that fungi are harmful organism. As biologist, explain six ways in which fungi are beneficial to humans
11. Briefly explain the HIV/AIDS basing on the following guidelines
Meaning, Mode of transmission, Symptoms, Preventive measures, Effects and Treatment/cure
9. (a)
(i) Diffuse growth and allometric growth:
- Diffuse growth refers to a situation where growth occurs evenly throughout an organism. For example, in plants, diffuse growth can be observed in the elongation of roots and shoots.
- Allometric growth refers to a situation where certain parts of an organism grow at different rates compared to other parts. An example of this is the growth of an insect, where the wings may grow at a different rate compared to the body.
(ii) Limited growth and unlimited growth:
- Limited growth refers to a situation where growth has a defined limit or stops after a certain point. An example of limited growth is observed in most animals, where growth stops after reaching a certain size.
- Unlimited growth refers to a situation where growth can continue indefinitely. This is seen in some organisms like plants, where they can keep growing throughout their lifespan.
(b)
(i) Sigmoid growth curve:
- The four significant phases of the sigmoid growth curve are the lag phase, exponential phase, deceleration phase, and stationary phase.
(ii) Rapid growth during adolescence stage:
- During adolescence, the rate of growth is rapid due to hormonal changes in the body. The release of growth hormones during puberty stimulates the growth of bones and muscles. This leads to a rapid increase in height and weight during this stage.
10. Fungi are beneficial to humans in several ways:
1. Decomposition: Fungi break down dead organic matter, such as fallen leaves and wood, and recycle nutrients back into the ecosystem.
2. Food production: Fungi are used in the production of various foods, such as bread, cheese, and fermented beverages like beer and wine.
3. Medicine: Fungi produce antibiotics, such as penicillin, which are used to treat bacterial infections.
4. Bioremediation: Some fungi have the ability to degrade pollutants and can be used to clean up contaminated environments.
5. Symbiotic relationships: Fungi form mutualistic relationships with plants, helping them absorb nutrients from the soil through structures called mycorrhizae.
6. Research and industry: Fungi are used in scientific research and in various industries, such as biotechnology, where they are used to produce enzymes, biofuels, and other valuable products.
11. HIV/AIDS:
- Meaning: HIV (Human Immunodeficiency Virus) is a retrovirus that attacks the immune system, specifically targeting CD4 T-cells. AIDS (Acquired Immunodeficiency Syndrome) is the advanced stage of HIV infection when the immune system is severely damaged.
- Mode of transmission: HIV can be transmitted thual contact, sharing of needles, from mother to child during childbirth or breastfeeding, and through blood transfusion.
- Symptoms: In the early stages of HIV infection, symptoms may be mild or absent. As the infection progresses, symptoms can include fever, fatigue, weight loss, swollen lymph nodes, and opportunistic infections.
- Preventive measures: Preventive measures include practicing safe sex, using sterile needles, using pre-exposure prophylaxis (PrEP), and promoting education and awareness about HIV/AIDS.
- Effects: HIV/AIDS weakens the immune system, making individuals more susceptible to infections and diseases. It can lead to various complications and can be fatal if left untreated.
- Treatment/cure: Currently, there is no cure for HIV/AIDS, but antiretroviral therapy (ART) can slow down the progression of the disease and improve the quality of life for individuals living with HIV.