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a) Carbon (iv) oxide:
i) Aim : to show that Carbon (IV) oxide is necessary for photosynthesis
ii) Material /apparatus
Potted plant, dark cupboards, potassium/sodium hydroxide pellets, iodine solution, water, methylated spirit, white tile, petroleum jelly, corks and source of heat
iii) Procedure
-destarch the potted plant by keeping it in a dark cupboard for 48hrs
-put pellets of NaOH/KOH into a conical flask A and distilled water in flask B
-fit the petioles of two different leaves of the potted plant in the grooves of corks and fit them as shown below;-
-seal the mouth of the conical flasks with petroleum jelly to make them air tight
-expose the apparatus to sunlight for about 3hrs
-remove the leaves from flask A and B and test each for the presence of starch using available reagents and materials
iv) Expected observation
leaf from flask A would retain iodine colour ; while leaf from flask B would turn blue.-black with iodine solutions.
iv) Conclusion
Starch is absent in leaf from flask A but present in leaf from flask B
KOH/NaOH pellets absorbed all CO2 hence no photosynthesis
b) Chlorophyll
i) Aim: to show chlorophyll is necessary for photosynthesis
ii) Materials and apparatus
Potted plant with variegated leaves, iodine solution, white tiles, water, methylated spirit and source of heat
iii) Procedure
-destarch the potted plant
-expose the plant to light for a period of 3 hrs
-pluck one or more variegated leaves from the plant and test for the presence of starch using the available materials and reagents
iv) Expected observation
green parts of the leaves would turn blue-black with iodine solution
while white or non-green parts would retain brown colour of iodine solution
iv) Conclusion
-photosynthesis took place in green plants but not in non-green parts
-chlorophyll is necessary for photosynthesis
c) Sunlight
i) Aim; to show that sunlight is necessary for photosynthesis
ii) Materials and apparatus
potted plant , clips or pins, black carbon paper, white tile, source of heat, water, iodine solution and methylated spirit
iii) Procedure
-destarch a potted plant
-using clips or pins , attach a piece of carbon paper on the upper surface of
one of the leaves to cover part of it as shown by the diagram below
-expose the setup to sunlight for a period of 3hrs
- pluck the experimental leaf, remove the carbon paper and test it for the
presence of starch using the available materials and reagents
iv) Expected observation
part which had been covered by black paper would turn brown while the
part exposed to sunlight would turn black
v) Conclusion
Starch is absent in part of the leaf which had been covered by black paper, indicating that no photosynthesis took place. Light is therefore necessary for photosynthesis
marto answered the question on September 25, 2019 at 09:10
- The table below shows how variation in environmental temperature relate to the body temperatures of two different types of animals A and B.(Solved)
The table below shows how variation in environmental temperature relate to the body temperatures of two different types of animals A and B.
(a) Using the information in the table above, plot a graph on same axes of body temperatures animals against environmental temperature.
(b) With reference to thermoregulation, state the general name given to animals of the A and B types.
A - type animals
B - type animals
(c) What three advantages do B-type animals have over A-type animals?
(d) Briefly describe how B-type
i) Physiologically respond to heat
ii) Physiologically respond to cold
Date posted: September 25, 2019. Answers (1)
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The diagram below shows an experiment set up using a seedling enclosed in a desk box with a hole on one side at the beginning of the experiment and after five days of growth.
(a) What type of response is shown by the above shoot?
(b) State two observable changes which took place in the seedling after five days of growth.
(c) Account for the observable changes in (b) above
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Date posted: September 25, 2019. Answers (1)
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The rates of gaseous exchange by different respiratory surfaces of plants were determined and recorded in the table below.
Suggest the possible plant structure represented by A, B, C.
Date posted: September 25, 2019. Answers (1)
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The figure below shows a model which was used by a group of Form 2 students to show the effect of or action of intercostal muscles on the movement of ribs.
(a) How does the sternum move when;
(i) String A is pulled tight.
(ii) String B is pulled tight.
(b) Between string A and B, which one represents;
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(ii) Internal intercostal muscles?
(c) What does structure Q represent in an animal
Date posted: September 25, 2019. Answers (1)
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(a) Work out the genotypes of the children in that family. (Use a punnet square
(b) Work out the phenotypic ratio and genotypic ratio of the resulting children from the crossing in (a) above
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Date posted: September 25, 2019. Answers (1)
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(a) Give an explanation for...(Solved)
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(a) Give an explanation for the absence of Red and white flowered plants in the F1 generation
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Date posted: September 25, 2019. Answers (1)
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The diagram below represents a stage in the development of human foetus.
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(b) Apart from the size of the foetus what else from the diagram illustrates that parturition was about to occur.
Date posted: September 25, 2019. Answers (1)
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Date posted: September 25, 2019. Answers (1)
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Date posted: September 25, 2019. Answers (1)
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Date posted: September 25, 2019. Answers (1)
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- The diagram below shows blood circulation in a bony fish. Use it to answer the questions that follow.(Solved)
The diagram below shows blood circulation in a bony fish. Use it to answer the questions that follow.
Name the structures labelled A and B.
Date posted: September 25, 2019. Answers (1)
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Study the diagram below and answer the questions that follow.
a) Name the process represented by the arrows.
b) Name the cell labelled 2.
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Date posted: September 25, 2019. Answers (1)
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student peeled off a piece of epidermis from an onion leaf and observed it under a microscope. He counted 10 cells across the diameter of the field of view. He then placed a transparent ruler across the field of view and observed the following.
Calculate the size of one cell in μm. show your working
Date posted: September 25, 2019. Answers (1)
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Date posted: September 25, 2019. Answers (1)
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Date posted: September 25, 2019. Answers (1)
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Date posted: September 25, 2019. Answers (1)
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An experiment to investigate a certain response by termites, was set up as shown below. The set up was exposed to the sun for some time.
a) What were the results at the end of the experiment?
b) Name the type of response exhibited by the termites.
c) Give one survival value of the response.
Date posted: September 25, 2019. Answers (1)
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Date posted: September 25, 2019. Answers (1)
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Date posted: September 25, 2019. Answers (1)