Biology Past Questions And Answers
When cells send a signal, it is often in the form of a secreted molecule. In some cases, a cell will secrete a molecule that binds to a receptor on its own cell surface. What type of signaling is this?
- A. Autocrine
- B. Paracrine
- C. Endocrine
- D. Exocrine
(a) Describe the processes that occur from the time a pollen grain is deposited on the stigma of a flower to the . formation of a zygote.
(b) Explain the importance of the amniotic sac to the mammalian embryo.
(c) The following are the names of some common diseases; malaria, typhoid, amoeboid dysentry, tuberculosis, tetanus, leprosy, cholera, yellow fever, poliomyelitis, measles, common cold, small pox, influenza, chicken pox, whooping cough and trypanosomiasis. Use the format below to classify the diseases according to their causative organisms.
| Viral diseases | Bacteria diseases | Protozoa diseases |
The period of inactivity seen in some animals during long period of heat or drought is
- A. Migration
- B. Aestivation
- C. Hibernation
- D. Adaptation
The exchange of gases between the environment and the respiratory organs of vertebrates is referred to as
- A. inhalation
- B. respiration
- C. expiration
- D. breathing
Which of the following is a feature of the population pyramid of a developing country?
- A. long lifespan
- B. low birth rate
- C. low death rate
- D. short lifespan
Birds maintain their body temperature with the help of their
- A. blood which maintains constant temperature
- B. feathers which cover the body
- C. skin which conserves moisture
- D. veins which transport fluid of constant temperature to all body tissues
Which of the following is a characteristic of cells related to irritability?
- A. Ability to respond to stimuli
- B. Ability to synthesize proteins
- C. Ability to generate energy
- D. Ability to replicate DNA
Haemophilia results from the mutation of the genes
- A. in the sex chromosome
- B. which control skin colour
- C. which control the mechanism for blood-clotting
- D. which control the formation of haemoglobin
The disadvantage of complexity of organisation in the higher organisms is that it leads to
- A. mutual interdependence between component cells
- B. internal structural specialization
- C. increased adaptation to environment
- D. slower rate of diffusion of oxygen to individual cells
Which of the following protects the essential parts of the flower at bud stage?
- A. Stamens
- B. Sepals
- C. Petals
- D. Carpels