Give scientific reasons for the following statements;
Mature erythrocytes in humans lack nucleus and mitochondria.
Lack of nucleus and mitochondria in R.B.C. cells helps to accommodate more haemoglobin pigment in its cell for the transport of respiratory gases. Lack of mitochondria help the R.B.C. cells to prevent the self utilization of oxygen for its own needs. Thus, the mature erythrocytes in humans lack nucleus and mitochondria.
Give scientific reasons for the following statements;
When an ovum gets fertilised, menstrual cycle stops temporarily in a 'woman'
Given below is a diagram depicting a defect of the human eye, study the same and answer the questions that follow:
(i) Name the defect shown in the diagram.
(ii) What are the two possible reasons that cause this defect?
(iii) Name the type of lens used to correct this defect.
(iv) With the help of a diagram show how the defect shown above is rectified using a suitable lens.
Give scientific reasons for the following statements;
Blood flows in arteries in spurts and is under pressure.
Give scientific reasons for the following statements;
lnjury to medulla oblongata leads to death.
State the main function of the following:
(i) Lymphocytes of blood
(ii) Leydig cells
(iii) Guard cells
(iv) Eustachian tube
(v) Corpus luteum
Given in the box below are a set of l4 biological terms. Of these, 12 can be paired into 6 matching pairs. Out of the six pairs. one has been done for you as an example.
Example: endosmosis - Turgid cell.
Identify the remaining five matching pairs:
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Cushing's syndrome, Turgid cell, Iris, Free of rod and cone cells, Colour of eyes, Hypoglycemia. Active transport, Acrosome. Addison's disease. |
Give scientific reasons for the following statements;
Colour blindness is more common in men than in women.
The figure given below is a diagrammatic representation of a part of the cross section of the root in the root hair zone. Study the same and then answer the questions that follow:
(i) Name the parts indicated by the guidelines 1 to 4.
(ii) Which is the process that enables the passage of water from the soil into, the root hair?
(iii) Name the pressure that is responsible for the movement of water in the direction indicated by the arrows. Define it.
(iv) Due to an excess of this pressure sometimes drops of water are found along the leaf margins of some plants especially in the early mornings. What is the phenomenon called?
(v) Draw a well labelled diagram of the root hair cell as it would appear if an excess of fertiliser is added to the soil close to it.
