NEET Biology Biotechnology Microbes and Ecology MCQs Set 01

Answer: (c) both IARI and KVIC

Explanation:
1. The Indian Agricultural Research Institute (IARI) and the Khadi and Village Industries Commission (KVIC) played the main role in developing biogas technology in India.
2. So both IARI and KVIC are correct.

Teacher's Note:
1. Biogas is mostly methane produced by methanogens such as Methanobacterium.
2. The plant is also called a gobar gas plant.

Answer: (d) both insects and some other arthropods

Explanation:
1. Baculoviruses (genus Nucleopolyhedrovirus) are species-specific, narrow spectrum insecticides.
2. They attack insects and other arthropods, and have no negative impact on plants, mammals, birds or fish.
3. So both insects and some other arthropods is correct.

Teacher's Note:
1. They are suited to integrated pest management and to organic farming.
2. They are safe for non-target organisms.

Answer: (b) Glomus

Explanation:
1. Glomus is a fungus that forms mycorrhizal associations with plant roots.
2. The fungal hyphae absorb phosphorus from the soil and pass it to the plant, and the plant supplies carbohydrates to the fungus.
3. Anabaena, Rhizobium and Frankia fix nitrogen.

Teacher's Note:
1. Mycorrhiza also helps resist salinity, drought and root pathogens.
2. Phosphorus uptake is its best known benefit.

Answer: (c) production of \(\ce{CO2}\)

Explanation:
1. Baker's yeast (Saccharomyces cerevisiae) ferments sugars in the dough and releases carbon dioxide.
2. The gas gets trapped in the dough and makes it rise.
3. LAB converts milk to curd and Monascus produces statins.

Teacher's Note:
1. Ethanol in the dough evaporates when baked.
2. The gas bubbles are responsible for the soft texture of bread.

Answer: (c) EcoRV

Explanation:
1. EcoRV cuts both strands at the same point in the middle of its recognition site (GAT^ATC), giving blunt ends.
2. EcoRI, BamHI and HindIII make staggered cuts and leave sticky (cohesive) ends.

Teacher's Note:
1. Sticky ends join more easily with DNA ligase.
2. Blunt ends can be joined too, but less efficiently.

Answer: (a) Restriction endonuclease

Explanation:
1. Restriction endonucleases were first found in E. coli as a defence that cuts the DNA of invading bacteriophages.
2. The bacterium protects its own DNA by methylation.
3. Ligase joins fragments, polymerase copies DNA and gyrase relieves supercoiling.

Teacher's Note:
1. The name restriction comes from restricting phage growth.
2. This observation led to the discovery of restriction enzymes.

Answer: (d) G and A only

Explanation:
1. The recognition sequence of EcoRI is 5'-GAATTC-3'.
2. It cuts between G and A on each strand, leaving sticky ends with a four-base overhang.

Teacher's Note:
1. The cut is staggered, giving 5' overhangs.
2. Palindromic sequences read the same on both strands in the 5' to 3' direction.

Answer: (d) Micro-injection

Explanation:
1. In micro-injection, recombinant DNA is injected directly into the nucleus of an animal cell.
2. Gene gun is for plant cells, and heat shock with calcium chloride is used for bacterial cells.

Teacher's Note:
1. Each host has its own method.
2. Disarmed Ti plasmid is another way to transfer genes into plants.

Answer: (b) Golden rice

Explanation:
1. Golden rice is rich in beta-carotene (provitamin A), which the body converts to vitamin A.
2. Vitamin A deficiency causes night blindness, so this rice can help.

Teacher's Note:
1. Golden rice has a yellow colour due to the carotene.
2. Flavr Savr is a delayed ripening tomato.

Answer: (a) Golden rice

Explanation:
1. Golden rice contains beta-carotene, which is a precursor of vitamin A.
2. Night blindness is caused by vitamin A deficiency, so Golden rice is the correct choice.

Teacher's Note:
1. The gene for the carotene pathway was introduced by genetic engineering.
2. The other crops address shelf life and pests.

Answer: (b) Atlas 66 : a wheat variety having high carbohydrate content

Explanation:
1. Atlas 66 is a wheat variety with high protein content, not high carbohydrate.
2. The other three descriptions are correct: an explant is the plant part used in tissue culture, micropropagation produces many plants, and Parbhani Kranti is a disease resistant okra variety.

Teacher's Note:
1. Atlas 66 is used as a donor of high protein content.
2. Pusa Swarnim and Pusa Shubhra are other bred varieties worth remembering.

Answer: (a) SCID

Explanation:
1. In 1990 gene therapy was first used for a four-year-old girl with ADA deficiency (severe combined immunodeficiency, SCID).
2. Lymphocytes were taken, given a functional ADA gene and returned to the patient.

Teacher's Note:
1. ADA deficiency disables the immune system.
2. Gene therapy replaces the defective gene with a functional copy.

Answer: (b) those that occur in a particular area

Explanation:
1. Endemic species are restricted to one particular region and are found nowhere else.
2. Cosmopolitan species are found all over the world.

Teacher's Note:
1. Endemism often occurs on islands and mountains.
2. It is important in discussions of biodiversity hotspots.

Answer: (b) Lichens

Explanation:
1. Lichens are the pioneer species on bare rock in xerarch succession.
2. They secrete acids that weather the rock and start soil formation.

Teacher's Note:
1. Lichens are called pioneer species.
2. Mosses come after lichens.

Answer: (a) Tropical rain forest

Explanation:
1. A tropical rain forest has several distinct layers: emergent trees, canopy, understorey, shrub layer and forest floor.
2. Other forests have fewer layers.

Teacher's Note:
1. Stratification is vertical layering of vegetation.
2. It is most developed where light, water and temperature are favourable all year.

Answer: (d) Productivity

Explanation:
1. The structure of a community includes species composition, stratification, dominance, species diversity and trophic structure.
2. Productivity is a function of the ecosystem (energy flow), not a structural feature of a community.

Teacher's Note:
1. Structure describes what is there, function describes what it does.
2. Productivity and decomposition are functional characters.

Answer: (d) Profundal

Explanation:
1. P/R is the ratio of photosynthesis to respiration.
2. The littoral and limnetic zones receive light, so photosynthesis is at least equal to respiration.
3. The profundal zone lies below the compensation depth, where light is too weak, so respiration exceeds photosynthesis and P/R is below 1.

Teacher's Note:
1. The compensation depth is where photosynthesis equals respiration.
2. The profundal zone is deep and dark.

Answer: (d) a, b and d

Explanation:
1. (a) is correct: parasites and their hosts evolve together.
2. (b) is correct: lichens are a mutualism between an alga and a fungus.
3. (c) is wrong: sexual deceit is shown by the orchid Ophrys, which mimics a female bee.
4. (d) is correct: copepods are ectoparasites on marine fishes.

Teacher's Note:
1. Remember Ophrys for sexual deceit.
2. Opuntia is a prickly pear and is an example of an introduced species in Australia.

Answer: (d) The climax community is a forest of mesophytes

Explanation:
1. Hydrarch succession starts in water and xerarch succession starts on dry rock.
2. Both of them end in a mesic condition, with a mesophytic climax community.
3. The pioneer stages are different, and only xerarch starts in dry areas.

Teacher's Note:
1. Both pathways converge to the mesic condition.
2. They differ in their starting point and pioneers.

Answer: (c) In hydrosere, a hydric environment progresses to mesic conditions

Explanation:
1. In hydrosere (hydrarch succession) the habitat starts as water and ends as mesic land.
2. In xerosere dry conditions progress to mesic, not hydric.
3. Abandoned farm land already has soil, so succession there is secondary.

Teacher's Note:
1. Primary succession begins on a bare area without soil.
2. Secondary succession starts where soil is already present.

Answer: (a) sharing of one or more resources between two species

Explanation:
1. A niche is the role and conditions of a species in its habitat.
2. When two species use the same food or other resource, their niches overlap.
3. The more the overlap, the more intense the competition.

Teacher's Note:
1. Gause's competitive exclusion principle follows from niche overlap.
2. Resource partitioning lets competitors coexist.