Carbon(IV)oxide increases in the guard cell; pH increases leading to conversion of glucose to starch; starch is osmotically inactive compared to glucose; this leads to guard cells loosing water to the surrounding epidermal cells; guard cells becomes flaccid and hene stoma closes.
sharon kalunda answered the question on March 22, 2019 at 06:34
- State the importance of the structure given below in a seed.
(a) Endosperm.
(b) Testa.(Solved)
State the importance of the structure given below in a seed.
(a) Endosperm.
(b) Testa.
Date posted: March 21, 2019. Answers (1)
- Two populations of the same species of birds were separated over a long period of time by an ocean. Both populations initially fed on insects...(Solved)
Two populations of the same species of birds were separated over a long period of time by an ocean. Both populations initially fed on insects only but later it was observed that one population fed entirely on fruits and seeds although insects were available. Name;
(a) The type of isolation.
(b) The type of evolutionary change.
(c) What are vestigial structures?
(d) Name one vestigial structure in man.
Date posted: March 21, 2019. Answers (1)
- Eight potato cylinder of the same size were used to investigate a certain physiological process. Four of the potato cylinders were placed in solution S....(Solved)
Eight potato cylinder of the same size were used to investigate a certain physiological process. Four of the potato cylinders were placed in solution S. The other four potato cylinders were placed in solution T. After 2 hours, the potato cylinders from solution S were found to longer and stiff, while those from solution T were found to be shorter and flexible. Explain the
results in solution S and T.
(b) Distinguish between active transport and diffusion.
Date posted: March 21, 2019. Answers (1)
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Why is the pancreas considered a dual gland?
Date posted: March 21, 2019. Answers (1)
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List two enzymes that are secreted in their precursor forms.
Date posted: March 21, 2019. Answers (1)
- The diagram below represents a type of bone in the mammalian skeleton.(Solved)
The diagram below represents a type of bone in the mammalian skeleton.
(a) Identify the bone illustrated in the diagram.
(b) Give a reason for your answer in (a) above.
Date posted: March 21, 2019. Answers (1)
- Three tubes each containing 1ml saliva and 1ml water were incubated in water baths at different temperatures as shown in the diagram below for 30...(Solved)
Three tubes each containing 1ml saliva and 1ml water were incubated in water baths at different temperatures as shown in the diagram below for 30 minutes. Another one tube containing 1ml starch solution was incubated for the same length of time in each water bath. The contents of the two tubes in each water bath was then mixed and incubated for further 30 minutes.The content of each tube was then tested for starch using iodine solution.
a) What was the aim of the experiment?
(b) Why was it necessary to incubate the tubes for 30 minutes before mixing their contents?
(c) State the colour changes you would expect to observe after adding iodine solution.
(d) Account for the expected observations.
Date posted: March 21, 2019. Answers (1)
- Sickle cell anaemia is a hereditary disease due to a recessive gene which changes normal haemoglobin (Hb – A) to abnormal
haemoglobin (Hb – S). The...(Solved)
Sickle cell anaemia is a hereditary disease due to a recessive gene which changes normal haemoglobin (Hb – A) to abnormal
haemoglobin (Hb – S). The red blood cells of people with sickle cell anaemia are sickle shaped.
(a) What are the possible phenotypes of the offsprings of a man who is heterozygous and a woman who is also heterozygous?
Show your working.
(b) Sickle cell trait is more prevalent in tropical countries than in temperate countries. Give an explanation for this observation.
Date posted: March 21, 2019. Answers (1)
- Below is a diagram of a sperm cell.(Solved)
Below is a diagram of a sperm cell.
a) Identify parts labeled X and Y.
(b) Explain how parts W and Z adapt the cell to its function.
(c) Using letter P identify or label on the diagram the part of the cell rich in DNA.
(d) State the function of part X.
Date posted: March 21, 2019. Answers (1)
- The figure shown below represents a kidney nephron. Use it to answer the questions that follow.(Solved)
The figure shown below represents a kidney nephron. Use it to answer the questions that follow.
(a) (i) X is made up of a tuft of capillaries. How do they differ from other capillaries in the body?
(ii) What structural difference exist between W and Z?
(iii) State the significance of the difference stated in (a) (ii) above.
(b) State three adaptations that enable P to perform its function.
(c) What is counter flow and in which part of the nephron does it occur.
Date posted: March 21, 2019. Answers (1)
- An experiment was carried out to investigate the effect of hormones on growth of lateral buds of three pea plants.
The shoots were treated as follows.
(a)...(Solved)
An experiment was carried out to investigate the effect of hormones on growth of lateral buds of three pea plants.
The shoots were treated as follows.
(a) Shoot A – Apical bud was removed.
(b) Shoot B – Apical bud was removed and gibberellic acid placed on the cut shoot.
(c) Shoot C – Apical bud was left intact.
The lengths of the branches developing from the lateral buds were determined at regular intervals. The results obtained are shown in the table below.
(i) Using the same axes, draw graphs to show the lengths of branches against time.
(ii) (a) What was the length of the branch in Shoot B on the 7th day?
(b) What would be the expected length of the branch developing from Shoot B on the 11th day?
(iii) Account for the results obtained in the experiment.
(iv) Why was Shoot C included in the experiment?
(v) What is the importance of gibberellic acid in agriculture?
vi)State two physiological processes that are brought about by the application of gibberellic acid on plants.
Date posted: March 21, 2019. Answers (1)
- Describe the role of hormones in the mammalian female reproductive cycle.(Solved)
Describe the role of hormones in the mammalian female reproductive cycle.
Date posted: March 21, 2019. Answers (1)
- The diagram shown below represents a male reproductive system.(Solved)
The diagram shown below represents a male reproductive system.
(a) Name the structure labelled X.
(b) Name two substances that pass through structure labelled Y.
Date posted: March 21, 2019. Answers (1)
- Name causative agents of each of the following diseases.
(a) Typhoid
(b) Malaria(Solved)
Name causative agents of each of the following diseases.
(a) Typhoid
(b) Malaria
Date posted: March 21, 2019. Answers (1)
- The set up shows an experiment to investigate photosynthesis.(Solved)
The set up shows an experiment to investigate photosynthesis.
i) What gas was collected in the test tube?
ii) What was the role of sodium hydrogen carbonate in the experiment?
Date posted: March 21, 2019. Answers (1)
- (a) Name the part of the eye in which the light sensitive cells are located.
(b) List the two types of sensory cells found in...(Solved)
(a) Name the part of the eye in which the light sensitive cells are located.
(b) List the two types of sensory cells found in the part named in (a) above.
Date posted: March 21, 2019. Answers (1)
- Which two classes of phylum arthropoda have their head fused with the thorax?(Solved)
Which two classes of phylum arthropoda have their head fused with the thorax?
Date posted: March 21, 2019. Answers (1)
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What biological knowledge or study is required in dealing with locusts that infest a maize crop.
Date posted: March 21, 2019. Answers (1)
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Describe an experiment you would carry out to demonstrate that xylem transports water
Date posted: March 19, 2019. Answers (1)
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What will happen in the stomach during digestion if mucus is absent?
Date posted: March 17, 2019. Answers (1)