Organisms and Populations — BIOLOGY STD 12 Science — Question

Explain the amplification of gene of interest using PCR (Diagram is must)

Read the following text carefully and answer the questions that follow:
The following is the illustration of the sequence of ovarian events (a-i) in a human female.

i. Identify the figure that illustrates ovulation and mentions the stage of oogenesis it represents. (1)
ii. Name the ovarian hormone and the pituitary hormone that have caused the above-mentioned event. (1)
iii. Explain changes that occur in the uterus simultaneously in anticipation. (2)
OR
Draw a labelled sketch of the structure of a human ovum prior to fertilization. (2)

Read the following and answer any four questions from (i) to (v) given below:

A woman unable to conceive after many years of regular unprotected coitus went to specialised infertility clinic. On complete examination, woman was found to be normal, while male partner was diagnosed with infertility. Male partner is unable to copulate the female. Couple was advised to opt for assisted reproductive technology (ART).

1. Which ART could have been useful for this couple?

1. ZIFT
2. IUT
3. AI
4. GIFT

2. In which of the following infertility issues could this technique be used?

1. Anovulation.
2. Oligospermia.
3. Low fructose content in seminal fluid.
4. All of these.

3. Which among the following techniques is useful to conceive when there is very low sperm count?

1. GIFT
2. Test-tube baby
3. IUT
4. JCSI

4. Assertion: Artificial insemination (AI) is intra-uterine insemination.

Reason: In Al, sperms collected from donor are introduced into the uterus.

1. Both assertion and reason are true, and reason is the correct explanation of assertion.
2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
3.  Assertion is true, but reason is false.
4. Both assertion and reason are false

5. Success rate of artificial insemination technique is:

1. 20-40%
2. 60-70%
3. 40-50%
4. 5-7%

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)

Explain Mutualism as a population interaction with suitable examples.###Explain Mutualism with examples

Read the following and answer any four questions from (i) to (v) given below:

Cleavage is the series of rapid mitotic divisions in zygote and forms blastula. The 2, 4, 8, 16 daughter cells are called blastomeres. Embryo with 64 blastomeres is known as blastocyst and has blastocoel cavity. Blastocyst gets implanted in uterine wall and leads to pregnancy.

1. Solid mass of cells with 16 blastomeres is called:

1. Morula.
2. Blastula.
3. Gastrula.
4. Zygote.

2. At which stage of embryonic development, trophoectoderm develops?

1. Zygote.
2. Morula.
3. Blastula.
4. Gastrula.

3. Site of implantation is:

1. Endometrium of uterus.
2. Cervix.
3. Uterine fundus.
4. Infundibulum of oviduct.

4. Correct sequence of various structures formed during embryonic development is:

1. Morula → Embryo → Gastrula → Blastula.
2. Zygote → Embryo → Morula → Blastula.
3. Blastula → Morula → Gastrula → Embryo.
4. Zygote → Morula → Blastula → Gastrula.

5. Assertion: Side of blastocyst with inner cell mass is called animal pole.

Reason: Inner cell mass gives rise to embryo.

1. Both assertion and reason are true, and reason is the correct explanation of assertion.
2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
3. Assertion is true, but reason is false.
4. Both assertion and reason are false.

Read the following text carefully and answer the questions that follow:
Cancer refers to any one of a large number of diseases characterized by the development of abnormal cells that divide uncontrollably and have the ability to infiltrate and destroy normal body tissue. Cancer often has the ability to spread throughout your body. Cancer is the second-leading cause of death in the world.

i. How does a cancerous cell differ from a normal cell? (1)
ii. Benign tumor is less dangerous than malignant tumor. Why? (1)
iii. Describe causes of cancer. (2)
OR
Mention two methods of treatment of the disease. (2)

Nematode specific genes were introduced into the tobacco host plant using a vector:

1. pBR 322.
2. Plasmid.
3. Bacteriophage.
4. Agrobacterium.

Read the following text carefully and answer the questions that follow:
The reproductive cycle in female primates (e.g. monkeys, apes and human beings) is called the menstrual cycle. In human females, menstruation is repeated at an average interval of about 28/29 days, and the cycle of events starting from one menstruation till the next one is called the menstrual cycle Anita has show Diagrammatic presentation of various events during a menstrual cycle.

i. What role do pituitary gonadotropins play during the follicular and ovulatory phases of the menstrual cycle? (1)
ii. The first half of the menstrual cycle is called the proliferative phase as well as the follicular phase. Give reason.(2)
iii. Why does corpus luteum stay active throughout pregnancy and in the absence of fertilization, is active only for 10-12 days?
OR
What happens to corpus luteum in human female if the ovum is (2)
a. fertilised,
b. not fertilised?

Read the following text carefully and answer the questions that follow:
When a microorganism invades a host, a definite sequence of events usually occur leading to infection and disease, causing suffering to the host. This process is called pathogenesis. Once a microorganism overcomes the defense system of the host, development of the disease follows a certain sequence of events as shown in the graph. Study the graph given below for the sequence of events leading to appearance of a disease and answer the questions that follow:

i. In which period, according to the graph there are maximum chances of a person transmitting a disease/infection and why? (1)
ii. Study the graph and write what is an incubation period. Name a sexually transmitted disease that can be easily transmitted during this period. Name the specific type of lymphocytes that are attacked by the pathogen of this disease. (1)
iii. Draw a schematic labelled diagram of an antibody. (2)
OR
In which period, the number of immune cells forming antibodies will be the highest in a person suffering from pneumonia?
Name the immune cells that produce antibodies. (2)