Question 1
Study the following food web and answer questions that follows;
- (i) Name the organisms that occupy the second trophic level.
(ii) What is the other name for the second trophic level. - Write down two food chains from the food web that
(i) Ends with hawks as tertiary consumer.
(ii) Ends with hawks as quaternary consumer.
Answer
- (i) Caterpillars
Aphids
Mice
Slug
(ii) Primary consumers -
(i) Plant → Caterpillars → Insectivious birds → Hawk
(ii) Plant → Aphids → Beetle → Insectivious birds → Hawk
Plant → Slug → Frogs → Snakes → Hawk
Question 2
Explain how Abiotic fixation nitrogen occurs.
Answer
Lightening provide high activation energy which causes Nitrogen to combine with oxygen forming various oxides of Nitrogen. The oxides combine with rain water to form nitric acid. The acid sinks in soil and reacts with various salt ions to form nitrate salts.
Question 3
The diagram below illustrates an experiment to determine the rate of respiration in a small insect
- Name the chemical labeled W and state its function
- Why is it necessary to place the flask in a water bath
-
(i) What observation do you expect in the level of coloured water in capillary tube after experiment has run for 5 minutes.
(ii) Explain the observation stated in C(i) above.
Answer
- W is Soda lime; Absorbs any carbon (IV) oxide present / produced by the animal.
- To maintain the temperature of the flask where the animal is at constant / room level.
-
(i) There will be a rise in the level of colored water.
(ii) The animal respires using up oxygen in the flask and producing carbon (iv) oxide which is absorbed by the soda lime; The air pressure in the flask falls; causing the atmospheric pressure to push fluid up the capillary tube.
Question 4
Other than age and occupation give two other factors that influence energy requirement in man.
Answer
- Body size
- Sex of individual
- Health
- Sex of individual
- Health
Question 5
A pea plant with round seeds was crossed with a pea plant that had wrinkled seeds. The gene for round seed is dominant over that for wrinkled seeds.
Using letter M to represent the dominant gene state:
- The genotypes of the parent if plant with round seeds was heterozygous.
- The gametes produced by the round seed and wrinkles seed plants
Round seed parent
Wrinkled seed parent - The genotypes and phenotypes of F1 generation. Show your workings.
Answer
- Round seed – Mm
Wrinkled seed – mm -
Round seed parent - M and m
Wrinkled seed parent - m and m -
