Biology Past Questions And Answers
The reduction of nitrates to gaseous nitrogen is
- A. nitrogen fixing
- B. nitrogen cycle
- C. ammonification
- D. denitrification
Which of the following measures does not ensure conservation?
- A. Establishing forest and game reserves
- B. Encouraging people to plant trees
- C. Founding societies that promote conservation
- D. Enclosing fishes in ponds where they will not be stolen
Which of the following statement is correct about diffusion?
- A. it involves movement of water molecules only
- B. Molecules move from a region of higher concentration to a region of lower concentration
- C. differentially permeable membrane must be present for diffusion to occur
- D. It involves when a solute can no longer dissolve in a solvent of only solute molecules into the Bowman's capsule
In which of the following scenarios is stabilizing selection most likely to take place?
- A. Male elk that have larger antlers are better able to fight for dominance. The most dominant elk in an area produces the most offspring.
- B. In a population of hawks, very large hawks are able to carry off large prey such as small deer, but very small hawks are slightly faster and so have more success hunting small mammals.
- C. A population of feral cats begins to hunt the mice in a neighborhood. Mice that are very small are unable to run fast enough to escape the cats, whereas mice that are very large are unable to fit in small nooks and crannies to hide from the cats.
- D. A few individuals in a population of coastal-dwelling moths is blown to an offshore island during a tropical storm
What will happen wen two equal sized pieces of unripe pawpaw labelled X and Y are dropped into equal volumes of concentrated salt solution and distilled water respectively?
- A. pawpaw X will become turgid
- B. both will increase in size
- C. pawpaw Y will become turgid
- D. both will decrease in size
The transmission of impulses along a nerve fibre is characterized by
- A. hormonal and temperature changes
- B. electrical and ionic changes
- C. hormonal and changes
- D. electrostatic changes
The presence of stilt roots, pneumatophores, sunken stomata and salt glands are adaptive features of plants found in the
- A. tropical rainforest
- B. mangrove swamps
- C. gressland
- D. montane forest
The cilia in paramecium are used for
- A) respirating
- B) locomotion
- C) protection
- D) regulating food in-take
Trace elements are required by plants mainly for the
- A. formation of pigments and enzymes
- B. production of energy and hormones
- C. manufactured of carbohydrates
- D. manufacture of proteins
When a marine fish was taken from the ocean and put in a tank of fresh water, it died after a short period because?
- A. the tank was too small compared to the large-ocean
- B. the body cells of the fish swelled and burst as a result of the hypotonic fresh water
- C. the body cells of the fish shrank as their sap was hypertonic to the freshwater
- D. there was no food in the tank, so the fish starved

