Definition of Mutation and other biology questions and answers

Define the term mutation

Is a sudden change in the genetic make up of an individual

A couple, George and Grace had a son who was suffering from haemophilia even though none of them
showed signs of haemophilia.
i) State the genotype of George and Grace.

Snap 2023 04 02 at 05.31.11

Using a genetic cross work out the genotype of the couple’s son.

genotype of the couple’s son

What are linked genes?

Genes located on the same chromosome and are transmitted together;

An experiment was set up to investigate the effect of unilateral light on the growth of oat coleoptile. The diagrams in the table below represent the experimental set ups at the start, and at the end of the experiment.

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a) Account for the results in the experimental setup A.

The coleoptile tip bends towards light/positive phototropism/positively phototropic; more cells elongating/more growth on the side away from light; due to high auxin concentration on the side away from light;

b) Explain the purpose of experimental set ups B and C.

B and C are control experimental set ups for A;
B shows that it is the tip that responds to light
C shows that it is the tip of that is the source of growth hormones/auxins/1AA;

c) Explain the results in experimental set ups D and E.

No curvature in D because hormones/Auxins/1AA from the tip do not reach region of cell elongation (due to mica blade); in E curvature occurred because mica blade does not interfere with the tip to region of cell elongation on the side away from light;

Three pieces of potato cylinders of equal length were placed in three solutions of different concentrations. The set ups were left to stand for 45 minutes. The results were recorded in the table below.

Three pieces of potato cylinders of equal length were placed in three solutions of different concentrations. The set ups were left to stand for 45 minutes. The results were recorded in the table below.

a) Describe the nature of solution A in relation to the concentration of the potato cells.

Isotonic solution;

b) Explain the observation that was made on the potato cylinder which was put in solution B.

Solution B was hypertonic; to potato cells. The cells lost water to solution B through osmosis; and became plasmolysed hence the reduction in length of the cylinder;

c) i) State what would happen to red blood cells if they were placed in solution C.

The cell would be haemolysed; cells would burst

ii) Explain your answer in (c)(i) above.

The solution is hypotonic to red blood cells; the cells would gain water by osmosis then swell and burst;

d) Name the process involved in uptake of mineral salts by plants from the soil.

Active transport; 

a) Explain the term double fertilization as applied in plants.

One male nucleus of the pollen grain fuse with the polar nuclei; to from triploid primary endosperm nucleus; while the other male nucleus fuse with the egg cell nucleus; to form the zygote; (that develop into embryo)

b) State the role of each of the following hormones in male humans.

i) Follicle stimulating hormone.

Stimulates the synthesis/maturation of sperms;

ii) Testosterone

Stimulates the development of secondary male characteristics;

c) What is in vitro fertilization?

Fertilization of ovum is done in a test tube; and the fertilized ovum is transferred into mother’s uterus;

d) Name the causative agent of gonorrhea.

Neisseria gonorrhea;

The diagram below shows part of gaseous exchange system in an insect. Study it and answer the questions that follow.

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a) What are the structural adaptations of the parts labelled A and B to their functions?

i) A has a Presence of rings of chitin which keeps them always open ;

ii) B has Moist epithelium for dissolution of respiratory gases;

b) Name the parts of the following animals that carry out the same function as part B above. (2mks)
i) Man…
ii) Tilapia fish……

i) alveoli;
ii) gill filaments

c) Name the structures used for gaseous exchange in plants growing in water logged soils.

pneumatophores;

d) i) Give two reasons why accumulation of lactic acid during vigorous exercise leads to an increase in heartbeat.

Lactic acid is poisonous to tissues and must be removed; to increase supply of oxygen to tissues;

ii) In what form is oxygen transported from lungs to the tissues?

Oxyhaemoglobin; Accept: HbO2/HbO8

During germination and growth of a cereal, the dry weight of the endosperm, the embryo and total dry weight were determined at two day intervals. The results are shown in the table below.

During germination and growth of a cereal, the dry weight of the endosperm, the embryo and total dry weight were determined at two day intervals. The results are shown in the table below.

a) On the same axes, draw graphs of dry weight of endosperm, embryo and the total dry weight against time.

graphs of dry weight of endosperm, embryo and the total dry weight against time.

b) What was the total dry weight on day 5?

38.5mg; ± 0.5          Reject: wrong units , Accept: without units

c) Account for:
i) Decrease in dry weight of endosperm from day 0 to day 10.

Hydrolysis of starch into simple sugar/glucose; which is translocated to the embryo; oxidation (of simple sugars) respiration to carbon (iv) oxide/energy/Heat

ii) Increase in dry weight of embryo from day 0 to day 10.

New cells materials/tissue are synthesized (from proteins); bringing about growth of embryo;

iii) Decrease in total dry weight from day 0 to day 8.

First leaf carried out photosynthesis (Leading to growth)

iv) Increase in dry weight after day 8.

d) State two factors within the seed and two outside the seed that cause dormancy.

i) Factors within the seed

i) presence of absiscic acid; Acc presence of germination inhibitors.
Embryo not fully developed;
Absence of hormones/enzymes that stimulate germination; impermeable seed coat; (Any two)

ii) Factors outside the seed

Unsuitable temperature/lack of suitable temp/ unfavourable temperature;
Lack of water;
Absence of light;
Lack of Oxygen;

e) Give two characteristics of meristematic cells

  • Dense cytoplasm;
  • Thin cell wall
  • absence of vacuoles
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