a. Explain briefly the importance of the following factors and organisms in the nitrogen cycle
(i) lightning; [3 marks]
(ii) Nitrosomonas; [2 marks]
(iii) Azotobacter. [2 marks]
b. Name the excretory organ in:
(i) insects: [1 mark]
(ii) earthworm.
c. Define
(i) hepatitis; [4 marks]
(ii) kidney stones [4marks]
d. (i) State three effects of lack of sense receptors in the skin to humans. [3 marks]
(ii) List three layers of the epidermis in the skin of humans. [3 marks]
a. (i) Lightning plays an important role in the nitrogen cycle because it helps to convert atmospheric nitrogen gas into reactive forms that can be used by plants and other organisms. This process, known as nitrogen fixation, is essential for the functioning of ecosystems.
(ii) Nitrosomonas is a type of bacterium that plays a key role in the nitrogen cycle by converting ammonia into nitrite, a more reactive form of nitrogen. This process is called nitrification and is important for the functioning of ecosystems.
(iii) Azotobacter is another type of bacterium that plays an important role in the nitrogen cycle by converting nitrates into nitrogen gas, a process known as denitrification. This helps to regulate the amount of nitrogen in the ecosystem and maintain balance.
b. (i) The excretory organ in insects is the Malpighian tubules.
(ii) The excretory organ in earthworms is the nephridia.
c. (i) Hepatitis is a medical condition in which the liver becomes inflamed. It can be caused by a variety of factors, including viral infections, alcohol abuse, and certain medications. Symptoms of hepatitis can include fatigue, jaundice, abdominal pain, and loss of appetite.
(ii) Kidney stones are hard deposits of minerals and salts that form in the kidneys. They can cause pain and discomfort as they move through the urinary tract, and can also lead to more serious health problems if left untreated. Symptoms of kidney stones include severe pain in the back or side, nausea, and frequent urination.
d. (i) Three effects of lack of sense receptors in the skin to humans include: decreased ability to feel touch, temperature, and pain; decreased ability to detect and respond to changes in the environment; and increased risk of injury and skin damage.
(ii) The three layers of the epidermis in the skin of humans are: the stratum corneum, the stratum granulosum, and the stratum basal.
e. (i) Metamorphosis is the process of transformation that some species of animals undergo during their development, in which they change from one form to another.
(ii)
- Grasshopper: incomplete metamorphosis
- Cockroach: incomplete metamorphosis
- Butterfly: complete metamorphosis
- Mosquito: complete metamorphosis
- Housefly: complete metamorphosis
Incomplete metamorphosis involves gradual changes from one form to another, without a pupal stage. Complete metamorphosis involves a transformation from a larval form to a pupal form, followed by the emergence of an adult form.
