Respiration and Circulation — BIOLOGY STD 12 Science — Question

Distinguish between : Pharynx and Larynx.

Distinguish between : Neutrophils and Eosionophils.

Microorganisms include bacteria, viruses, fungi and protozoa. In our mind, we presume, most of the time, that microbes are always harmful. Microbes are, of course, the causal agents of many infections diseases of plants and animals including humans but they also have lots of beneficial role. Lactic acid bacteria (LAB) are one of this kind of useful group. These are Gram positive, non-sporulating, either rod-shaped or spherical bacteria. They produce lactic acid in milk products as major metabolic end product of carbohydrate fermentation. LAB are considered as natural fermentors. Lactobacillus is a common LAB which converts lactose sugar of milk into lactic acid, that causes coagulation and partial digestion of milk protein casein. Milk is then changed into curd, yoghurt and cheese. Lactobacillus is also used in probiotics which have potentially beneficial effect on gut ecosystem of humans. Some other probiotic strain used belong to the Genus Bifidobacterium.

1. Which of the following is not considered as microorganisms?

1. Bacteriophage.
2. Streptococcus.
3. Porphyra.
4. Staphylococcus.

2. Select the incorrect option regarding the characteristics of lactic acid bacteria.

1. They are rod-shaped or spherical.
2. They are Gram positive.
3. They take part in carbohydrate fermentation.
4. They are acid intolerant.

3. Which of the following is not a lactic acid producing bacteria?

1. Streptococcus.
2. Lactococcus.
3. Saccharomyces.
4. Enterococcus.

4. Probiotics are:

1. Gut friendly live bacteria.
2. Acid balancing alternated bacteria.
3. Beneficial amount of dead bacteria.
4. Gram negative attenuated bacteria.

5. Assertion: Lactobacillus bacteria do not retain crystal violet stain while staining.

Reason: Lactobacillus have a very thin layer of peptidoglycan layer in their cell wall.

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 and answer any four questions from (i) to (v) given below:
Green manuring is the fanning practice where a leguminous plant which has derived enough benefits from its association with appropriate species of Rhizobium, is ploughed into the field soil and then a non-legume is sown and allowed to get benefitted from the already present nitrogen fixer. Some legumes, such as, Crotolaria juncea, Sesbania rostrata, Lencaena leucocephala, etc. are used as green manure. Rhizobia, that fix atmospheric nitrogen in the form of nitrate, live in the roots ofleguminous plants. These nutrients are used by non-leguminous plants through the practice of green manuring.

1. Green manures mainly provide nutrient enriched in:

1. Magnesium.
2. Sulphur.
3. Nitrogen.
4. Both (a) and (b).

2. Which of the following plants is used as green manure in crop fields?

1. Saccharum.
2. Dichanthium.
3. Phyllonthus.
4. Crotolaria.

3. Green manure plants belong to the Family:

1. Lamiaceae.
2. Papilionaceae.
3. Liliaceae.
4. Poaceae.

4. Due to excess use of chemical fertilisers rich in nitrate, ________ disease occurred in children.

1. Jaundice.
2. Septicemia.
3. Methemoglobinemia.
4. Botulism.

5. A green manure is:

1. Rice.
2. Maize.
3. Sorghum.
4. Sesbania.

Read the following and answer any four questions from (i) to (v) given below:
Organism P has thick lips and tongue so that it can easily feed on the commonly available spiny plants. Organism Q has thick layer of insulating fat under the skin. It was strong hooves to walk steadily on steep surfaces and lives in burrows during winters. Organism R has bright colours and sticky pads on its fingers and toes. It lives on trees.

1. Which of the following is correct habitat for organisms P regarding its adaptation?

1. Grassland biome.
2. Desert biome.
3. Tropical rainforest.
4. Tropical deciduous forest.

2. Which of the following is correct match regarding organism Q and its habitat?

1. Tundra - Polar bear.
2. Tropical rain forest - Deer.
3. Grassland - Bighorn sheep.
4. Desert - Camel.

3. Which of the following is incorrect regarding organisms R's habitat?

1. The vegetation shows stratification.
2. Epiphytic growth is rich.
3. Standing crop is highest.
4. Deep rooted shrubs are common due to abundant sunlight.

4. The dominant plants in habitat where P lives could be:

1. Opuntia
2. Nymphaea
3. Deodar
4. both (a) and (c).

5. Organisms P, Q and R respectively most likely occur in:

1. F, B and A.
2. C, A, E.
3. A, F and C.
4. B, D and A.

Read the following and answer any four questions from S(i) to S(v) given below:
Rajat is a student of biotechnology. His professor tells him that for transformation with recombinant DNA the bacterial cells must be made capable of taking up DNA as DNA do not pass through membrane. While doing experiment in the lab, Rajat noticed that bacterial cells were not taking up the foreign DNA even after treating it with sodium ion. He asked his professor, the reason behind this. His professor explained that he should check the valency and charge of the ion that he is using for the treatment.

1. It is difficult for DNA to pass through the membrane as

1. It is a hydrophilic molecule.
2. It is a hydrophobic molecule.
3. It is a circular molecule.
4. It changes its shape when it comes in contact with host cell.

2. What type of ions are used for DNA mediated gene transfers?

1. Divalent anions.
2. Divalent cations.
3. Monovalent cations.
4. Monovalent anions.

3. rDNA stands for,

1. reduced DNA
2. red DNA
3. recombinant DNA
4. related DNA.

4. Which of the following statements with regard to DNA is correct?

1. DNA is a positively charged molecule having two polynucleotide chains.
2. Nitrogen bases of two polynucleotide chain form complementary pairs, i.e., A opposite G and T opposite C.
3. Backbone of DNA chain is built up of alternate deoxyribose sugar and phosphate group.
4. Both (a) and (c)

5. Assertion: Competent host is essential for transformation with rDNA.

Reason: Transfer of DNA in a prokaryotic cell is called transfection.

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.