Question 1
- What is meant by the term sex linkage
- Name two sex-linked traits in humans associated to Y-chromosomes
- In Drosophila melanogaster, the inheritance of eye colour is sex linked. The gene for red eye is dominant. A cross was made between a homozygous red-eyed female and white eyed male. Work out the phenotypic ratio of F1 generation (use R to represent the gene for red eye)
Answer
- Gene located on the sex chromosomes and are transmitted along with those determining sex
- Baldness/premature baldness
Tuft of hairs sprouting from pinna/nose/ears - Parental phenotype: Red eyed female X White eyed male
Question 2.
-
Complete the table below showing Blood transfusion, tick (√) means no agglutination, cross (x) means agglutination
- The type of circulatory system found in member of the class insecta is
-
Name the blood vessel that transports blood
(i) From the small intestines to the liver
(ii) With the highest concentration of carbon (IV) oxide - Explain why the wall of the left ventrical is thicker than that of the right ventricle
Answer
- Open circulatory
-
(i) Hepatic portal vein;
(ii) Vena cava; - Left ventrical pumps blood a longer distance to all parts of the body; thicker walls exerts greater pressure
Question 3
- Distinguish between a community and a population
- Describe how a population of grasshoppers in a given area can be estimated
Answer
-
Community – consist of all plants and animals in a habitat interacting with each other / All organisms of different species in an habitat;
Population refers to members of the same species in an ecosystem -
– use of capture and recapture method;
- capture the grasshoppers;
- Count and mark;
- Use permanent ink to mark;
- record and release; and allow time to mix with entire population;
- recapture and count the marked and unmarked;
- Total population is equal to members of marked and unmarked grasshoppers in first sample; ÷ number of grasshoppers in second sample that were recaptured
Question 4
The diagram below represents growing seedlings which were subjected to unilateral light at the beginning of an experiment
-
(i) State the results of P, Q and R after 5 days
(ii) Account for your answer in a (i) above - If the tin foil were removed from the tip of seedling R what results would be observed after 2 days
- State the expected results after 3 days if the box were removed
Answer
-
(i)
- P - Will bent/ grow towards light
- Q - Will remain straigjht / no growth / little growth
- R - Will remain straight / grows straight / grows upwards
- In P –growth substances (hormones) / Auxins / IAA are produced by the stem tips; they move (downwards and get distributed) to the side away from the side of light / to the darker side; which they cause rapid (more) growth / (more) cell division / (more) cell elongation that results in bending
- In Q - The source of auxin (tip of stem) has been removed
- In R - The auxins cannot be affected by light because the tip has been covered
- It will bend towards the light / grows towards light by bending
- All the seedlings will grow straight / upwards
Question 5
The diagram below shows two fused bones of a mammal
- Identify the fused bones
-
Name the
(i) Bone that articulates at the point labeled F
(ii) The hole labeled G - Name the three types of muscles found in the body of a human
-
(i) State one difference between a ball and socket joint and a hinge joint
(ii) Name the structure at the knee that performs the same function as the olecranon process
Answer
- pelvic girdle
-
(i) femur;
(ii) obtular foramen -
- Cardiac muscle / heat muscles
- Smooth muscle / involuntary muscle / visceral muscle
- Skeletal mode / voluntary muscle -
(i) Ball and socket rotates 3600 / allow movement in all plane while hinge rotate 1800 / allow movement in one plane only;
(ii) Patella;