Case study (4 Marks)

Question 14 Marks

Read the following text carefully and answer the questions that follow:
The pathogen of a disease depends on RBCs of human for growth and reproduction. The person with this
pathogen suffers with chill and high fever.

i. Identify the disease. (1)
ii. Name the pathogen. (1)
iii. What is the cause of fever? (2)
OR
Represent the life cycle of the pathogen diagrammatically. (2)

Answer

i. Malaria
ii. Different species of Plasmodium viz P. vivax, P Malariae and P. falciparum.
iii. Malaria is caused by the toxins (haemozoin) produced in the human body by the malarial parasite. This toxin is released by the rupturing of RBCs.
OR
Life cycle of Plasmodium
iv.

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Question 24 Marks

Read the following text carefully and answer the questions that follow:
The image below shows the menstrual cycle of a human female. On the basis of this cycle:

i. Explain the menstrual phase in a human female. State the level of ovarian and pituitary hormones during this phase. (1)
ii. Why is follicular phase in the menstrual cycle also referred as proliferative phase? Explain. (1)
iii. Explain the events that occur in a Graafian follicle at the time of ovulation and thereafter. (2)
OR
Draw a Graafian follicle and label antrum and secondary oocyte. (2)

Answer

i. The reproductive cycle in female primates, e.g. monkeys, apes and human beings is called the menstrual cycle.
Menstrual phase starts from 3rd day and ends on 5th day. It is initiated due to reduced secretion of progesterone and estrogen from the regressing corpus luteum in the ovary. The endometrium breaks down and blood along with degenerated ovum constitute the menstrual flow.
The secretion of pituitary hormones, i.e. FSH and LH is also reduced during this phase.
ii In follicular phase, primary follicles in the ovary grow under the influence of Follicle Stimulating Hormone (FSH). It starts from 6th day of the menstrual date and ends on 13th or 14th day of a 28-day cycle.
iii. At the time of ovulation following events occurred in Graafian Follicle:
a. LH and FSH reached peak levels (about 14th-16th day of cycle).
b. High level of LH induces Graafian follicle to rupture and the release of a secondary oocyte from it.
c. After ovulation, the remaining cells of Graafian follicle are stimulated by LH to develop corpus luteum (an endocrine gland to secrete progesterone hormone).
OR
A diagrammatic sectional view of Graafian follicle

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Biology Case study (4 Marks)

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