Microbes in Human Welfare — BIOLOGY STD 12 Science — Question

For food related services, granting patent for transgenic organisms is becoming complicated. Explain with example.

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

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

Describe tissue culture.

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

The endosperm makes the main source of food for the embryo. Generally the endosperm nucleus divides after the division of the oospore, but in several cases the endosperm is formed to a great extent even before the first division of the oospore. There are three general types of endosperm formation: (a) nuclear type, (b) cellular type and (c) helobial type. The endosperm is usually triploid, but haploid endosperm is also found. Endosperm may either be completely consumed by the developing embryo before seed maturation, or it may persist in the mature seed.

1. Haploid endosperm is found in:

1. Pin us.
2. Cauliflower.
3. Sunflower.
4. Pea.

2. Persistent endosperm is found in:

P. Pea Q. Castor R. Bean S. Coconut T. Groundnut.

1. Q and S.
2. P and T.
3. R, S and T.
4. P, S and T.

3. Milk of tender coconut represents (A) and the surrounding white coconut meal represents (B).

S. No	A	B
(a)	Cellular endosperm	Free- nuclear endosperm
(b)	Free-nuclear endosperm	Cellular endosperm
(c)	Helobial endosperm	Cellular endosperm
(d)	Free-nuclear endosperm	Helobial endosperm

4. If an endosperm cell of a gymnosperm contains 12 chromosomes, the number of chromosomes in each cell of the root will be:

1. 4
2. 24
3. 16
4. 6

5. In angiosperms, normally after fertilization:

1. The zygote divides earlier than the primary endosperm nucleus.
2. The primary endosperm nucleus divides earlier than the zygote.
3. Both the zygote and primary endosperm nucleus divide simultaneously.
4. Both the zygote and primary endosperm nucleus undergo a resting period.

What is transgenic animals? How it is useful for man kind?

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)

Read the following and answer any four questions from 6(i) to 6(v) given below:

Rama lives in a society where a robbery occurred last night. Robbers came into the flat and murdered the old lady residing there. Police came and restricted the entry into the flat. They took samples from the room, where the dead body was found. While examining, they found that there is some blood and tissue in the nails of old lady. According to their observation, police filtered out their inspection to three suspects viz. servant, cook and milkman. Finally after two days of robbery, police caught the criminal. It was the old lady's cook. Rama was amazed to see that how quickly police completed and shut the case. She asked the inspector that how they did it? The police man told her that it become possible due to the sample collected from the victim, that lead them to the criminal. TI1e sample taken from nail scraping was amplified using PCR and then tested.

1. What technique was used by the police to identify the criminal?

1. DNA fingerprinting.
2. Gel electrophoresis.
3. Molecular diagnosis.
4. Clonning.

2. In PCR, the temperature used to denature the DNA is about:

1. 76º
2. 25º
3. 95º
4. 40º

3. Which of the following statements regarding PCR is correct?

1. Taq polymerase, which is isolated from bacterium Thermus aquaticus is stable at low temperature only.
2. With the help of DNA ligase, the complementary sticky ends of the DNA are joined to produce a rDNA.
3. Since the sequence of primers are complementary to 5' end of the template DNA, they anneal to it.
4. DNA purified from the cell is precipitated by adding hot ethanol.

4. Taq polymerase synthesises DNA region between the primers using:

1. Mg²⁺
2. dNTPs
3. DNA ligase
4. Both (a) and (b).

5. Given below are steps of polymerase chain reaction.

Select the option that correctly mention the sequence in which they occur.

1. (ii) → (iii) → (i)
2. (i) → (ii) → (iii)
3. (iii) → (i) → (ii)
4. (ii) → (i) → (iii)

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

Rajesh, Ravi, and Rohit are roommates. 'They are doing their graduation. Few months back Ravi fell ill. it took him around 3 weeks to recover. Both his friends were absolutely healthy at that time. After sometime, Rajesh also fell ill from some other disease. This time Ravi and Rohit both contracted the same illness. Based on the above information, answer the following questions.

1. Which of the following holds true for Ravi's illness?

1. Ravi was suffering from a communicable disease that is transmitted through vector.
2. Ravi was suffering from a communicable disease that is transmitted through faecal oral route.
3. Ravi was suffering from a non-communicable disease like anaemia.
4. Ravi was suffering from a non-communicable disease like Down's syndrome.

2. Select the correct statement.

1. Ravi contracted a disease caused by air borne microbes.
2. Ravi could have suffered a nutritional disorder.
3. Ravi suffered a non-contagious disease.
4. Both (b) and (c)

3. Which could be correctly said for Rajesh's illness?

1. Rajesh's illness was due to a microbial infection.
2. Rajesh's illness could be contagious or non-contagious.
3. Rajesh's illness could be cured by antibiotics.
4. All of these

4. Which of the following may depicts Ravi's and Rajesh's illness?

S.no	Ravi	Rajesh
(a)	Which of the following may depicts Ravi's and Rajesh's illness?	Myocardial infection
(b)	Whooping cough	Tetanus
(c)	Gastritis	Rhinitis
(d)	Hypertensio	Thyroid

5. Assertion: Diabetes mellitus is a non-communicable disease which can be completely cured.

Reason: Diabetes mellitus is caused by deficiency of aldosterone hormone.

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:
Malaria and dengue fever are major mosquito-borne public health problems in tropical countries. The authors report a malaria and dengue co-infection in an 11-year-old boy who presented with sustained fever for 10 days. The physical examination revealed a flushed face, injected conjunctivae and left submandibular lymphadenopathy. His peripheral blood smear showed few ring-form trophozoites of Plasmodium falciparum. His blood tests were positive for dengue NS-1 antigen and IgM antibody, and negative for IgG antibody. After the initiation of antimalarial treatment with artesunate and mefloquine, his clinical condition gradually improved. However, he still had low-grade fever that persisted for 6 days. Finally, he recovered well without fluid leakage, shock or severe bleeding.
i. Name the fish that help in eradication of mosquito larvae.
ii. What is the reason of symptoms of malaria?
iii. Name the body parts and host in which following events takes place in life cycle of plasmodium.
a. asexual reproduction
b. sexual reproduction.
OR
Name some vector borne diseases and their vector.

Bacteria cannot be seen with the naked eyes, but these can be seen with the help of a microscope. If you have to carry a sample from your home to your biology laboratory to demonstrate the presence of microbes with the help of a microscope, which sample would you carry and why?