Organisms and Populations — Page 2 | NEET Biology

Q11

When does the growth rate of a population following the logistic model equal zero?

A when N/K is exactly one.

B when N approaches the carrying capacity of the habitat.

C when N/K equals zero.

D when death rate is greater than birth rate.

Correct Answer

Option A

Solution

(a) dN/dt=0 when N/K=1, i.e., N=K.

Q12

Cuscuta is an example of

A ectoparasitism

B brood parasitism

C predation

D endoparasitism

Correct Answer

Option A

Solution

(a) Cuscuta (dodder) is a total stem ectoparasite.

Q13

Asymptote in a logistic growth curve is obtained when the population reaches carrying capacity:

A K=N

B K>N

C K<N

D The value of r approaches zero

Correct Answer

Option A

Solution

(a) When N=K, (K-N)/K=0, so dN/dt=0 — population reaches asymptote.

Q14

Which one of these animals is not a homeotherm?

A Macropus

B Chelone

C Psittacula

D Camelus

Correct Answer

Option B

Solution

(b) Chelone (turtle) is a reptile — ectothermic poikilotherm (cold-blooded).

Q15

A pair of insectivorous plants is

A Drosera and Rafflesia

B Nepenthes and Bladderwort

C Dionaea and Viscum

D Venus fly trap and Rafflesia

Correct Answer

Option B

Solution

(b) Nepenthes (pitcher plant) and bladderwort (Utricularia) are both insectivorous.

Q16

In India, human population is heavily weighed towards the younger age groups as a result of

A short life span of many individuals and low birth rate

B long life span of many individuals and low birth rate

C short life span of many individuals and high birth rate

D long life span of many individuals and high birth rate

Correct Answer

Option C

Solution

(c) High birth rate + short life span → heavily young-weighted population pyramid.

Q17

The concept that population tends to increase geometrically while food supply increases arithmetically was put forward by

A Stuart Mill

B Adam Smith

C Charles Darwin

D Thomas Malthus

Correct Answer

Option D

Solution

(d) Thomas Malthus (1778) proposed population grows geometrically, food arithmetically.

Q18

In a growing population of a country,

A pre-reproductive individuals are more than the reproductive individuals.

B post-reproductive individuals are less than the reproductive individuals.

C pre-reproductive individuals are fewer than the reproductive individuals.

D reproductive and pre-reproductive individuals are equal in number.

Correct Answer

Option A

Solution

(a) Growing population has more pre-reproductive (young) individuals than reproductive ones.

Q19

The maximum growth rate occurs in

A stationary phase

B senescent phase

C lag phase

D exponential phase

Correct Answer

Option D

Solution

(d) Maximum growth rate is during the exponential (log) phase.

Q20

A biologist studied the population of rats in a barn. He found that the average natality was 250, average mortality 240, immigration 20 and emigration 30. The net increase in population is :

A 15

B 05

C Zero

D 10

Correct Answer

Option C

Solution

(c) (250+20)-(240+30)=270-270=0.