NEET Biology Ecology Environment and Human Health MCQs Set 01

Answer: (b) The use of drugs like anti-histamine, adrenaline and steroids increases the symptoms of allergy

Explanation:
1. Allergy is an exaggerated immune response to allergens such as dust, pollen and mites; it involves IgE and release of histamine and serotonin from mast cells.
2. Anti-histamines, adrenaline and steroids reduce the symptoms of allergy quickly; they do not increase them.
3. So statement (b) is false; the other three are true.

Teacher's Note:
1. Anti-histamines block the action of histamine.
2. Rheumatoid arthritis is an auto-immune disorder in which the body attacks its own joints.

Answer: (d) hepatitis-B vaccine

Explanation:
1. A subunit vaccine contains only a part of the pathogen, such as a surface protein, rather than the whole organism.
2. The hepatitis-B vaccine is made from the surface antigen (HBsAg) produced in yeast by recombinant DNA technology.
3. BCG is a live attenuated vaccine, OPV is a live attenuated virus vaccine, and IPV is an inactivated whole-virus vaccine.

Teacher's Note:
1. Subunit vaccines are safe because they cannot cause the disease.
2. Recombinant yeast produces the HBsAg protein.

Answer: (a) Pneumonia - Haemophilus influenzae - droplet infection

Explanation:
1. Pneumonia is caused by Streptococcus pneumoniae and Haemophilus influenzae and spreads by droplets from an infected person.
2. Typhoid spreads through contaminated food and water, not through air. Malaria is transmitted by the bite of the female Anopheles mosquito. Filariasis is transmitted by the bite of the Culex mosquito.

Teacher's Note:
1. Only female mosquitoes bite, because they need blood for egg development.
2. Typhoid is diagnosed by the Widal test.

Answer: (c) a, b and c

Explanation:
1. In the species-area relationship \( \log S = \log C + Z \log A \), the slope Z of the line is similar for small areas, lying between 0.1 and 0.2, irrespective of the taxonomic group or region.
2. So plants in Britain, birds in California and molluscs in New York all have a similar Z.

Teacher's Note:
1. Z for very large areas such as continents is steeper: 0.6 to 1.2.
2. Alexander von Humboldt discovered the species-area relationship.

Answer: (b) C - all birds and mammals

Explanation:
1. Line A (internal level rising in step with external level) shows conformers; line B (constant internal level) shows regulators; line C shows partial regulators (regulate up to a limit and then conform).
2. Regulators such as birds and mammals follow line B, not C. So the statement 'C - all birds and mammals' is incorrect. 99% of animals and nearly all plants are conformers (A).

Teacher's Note:
1. Regulators maintain homeostasis by physiological means; conformers cannot.
2. Partial regulators regulate only within a limited range.

Answer: (b) Nearly 42% of insects are phytophagous

Explanation:
1. The Mediterranean orchid Ophrys mimics the female bee, so pollination and the bee's behaviour co-evolve. Predators transfer energy from lower to higher trophic levels. In interference competition one species harms the other's access to resources even when the resources are abundant.
2. Nearly 25% of insects (not 42%) are phytophagous (plant-eating), so statement (b) is incorrect.

Teacher's Note:
1. Insects that feed on plant sap and other parts are phytophagous.
2. Interference competition does not require the resource to be limiting.

Answer: (d) species diversity

Explanation:
1. The four basic functional components (processes) of an ecosystem are productivity, decomposition, energy flow and nutrient cycling.
2. Species diversity is a structural feature of the ecosystem (together with stratification and species composition).

Teacher's Note:
1. Structure: species composition, stratification. Function: productivity, decomposition, energy flow, nutrient cycling.
2. Diversity describes composition, not a process.

Answer: (b) 3

Explanation:
1. In a grassland ecosystem the pyramid of numbers is upright: the number of organisms decreases at each higher trophic level.
2. The top (tertiary) consumers are very few, with a value of about 3 individuals, following 354,000 secondary consumers.

Teacher's Note:
1. The pyramid of numbers in a grassland is upright, unlike that of a tree ecosystem.
2. Numbers fall sharply because energy decreases at every transfer.

Answer: (c) methane, hydrogen sulphide and \( \ce{CO2} \)

Explanation:
1. In the anaerobic digester, bacteria digest the organic matter of the activated sludge.
2. They produce a mixture of gases called biogas: methane, hydrogen sulphide and carbon dioxide. Oxygen is absent because the process is anaerobic.

Teacher's Note:
1. Biogas can be used as a source of energy.
2. Anaerobic bacteria such as methanogens produce methane.

Answer: (c) stork

Explanation:
1. Biomagnification: the concentration of a non-degradable toxin increases at successive trophic levels.
2. Of the choices, the stork is at the highest trophic level in the aquatic food chain, so it has the highest DDT concentration.

Teacher's Note:
1. DDT is not metabolised and accumulates in fatty tissues.
2. High DDT concentration thins the eggshells of birds.

Answer: (b) 1987

Explanation:
1. The Montreal Protocol was signed in 1987 (Canada) and came into effect in 1989.
2. It controls the emission of ozone-depleting substances such as CFCs.

Teacher's Note:
1. The Kyoto Protocol (1997) is about greenhouse gases.
2. The Montreal Protocol was effective in reducing CFCs.

Answer: (a) gases like sulphur dioxide

Explanation:
1. A scrubber passes the exhaust through a spray of water or lime. Gases such as sulphur dioxide dissolve in it or react and are removed.
2. Particulate matter is removed by electrostatic precipitators and filters, not by scrubbers.

Teacher's Note:
1. Scrubbers remove soluble gases like \( \ce{SO2} \).
2. Electrostatic precipitators remove over 99% of particulate matter.

Answer: (d) \( \frac{dN}{dt} = rN \)

Explanation:
1. With unlimited resources the population grows exponentially (geometrically): \( \frac{dN}{dt} = rN \).
2. The equation with the factor \( \frac{K-N}{K} \) is the logistic (Verhulst-Pearl) growth equation, which is sigmoid.

Teacher's Note:
1. Exponential growth gives a J-shaped curve and logistic growth an S-shaped curve.
2. K is the carrying capacity.

Answer: (a) a, b, c, d and f

Explanation:
1. A population is a group of individuals of the same species living in a definite area and able to interbreed.
2. (a), (b), (c), (d) and (f) each refer to one species in one place. (e) 'All animals in a forest' includes many species, so it is a community.

Teacher's Note:
1. Population: one species. Community: all species in an area.
2. Always check whether the example names a single species.