density until it is zero.
(iii) The slope of the tangent sigmoid growth form at any point represents the rate
of growth at

that point in time.
(iv) As long as growth continues as a straight line on a semilog plot it can be said to
be

exponential.
A:-Only (i) and (ii)
B:-Only (ii) and (iii)
C:-Only (ii), (iii) and (iv)
D:-Only (i)
Correct Answer:- Option-D

Question42:-Organic by-products may also increase the availability of minerals for
uptake by autotrophs through a process in which the organic molecules grasp or
form complexes with minerals. This process is known as

A:-Chelation
B:-Sequestration
C:-Leaching

D:-None of the above
Correct Answer:- Option-A

Question43:-Which of the following statement(s) is/are correct about population
characteristics?

(i) Density : Population size in relation to a unit of space.

(ii) Natality : The rate at which new individuals are added to the population by
reproduction.

(iii) Population growth rate or growth form : The net result of natality, mortality and
dispersal.

(iv) Dispersal : The rate at which individuals are lost by death.

A:-Only (i) and (ii)
B:-Only (i), (ii) and (iii)
C:-Only (ii) and (iii)
D:-Only (iv)

Correct Answer:- Option-B

Question44:-There are two statements marked as Assertion (A) and Reason (R).
Mark your answer as per the codes provided below :

Assertion (A) : In the process of nitrification, soil bacteria convert v#; or wxt to
nitrate (vo;), a form of nitrogen also commonly used by plants.

Reason (R) : Bacteria in the genera Nitrosomonas and Nitrococcus first oxidize the
forms of ammonia to nitrite (vo.) , after which bacteria in the genus Nitrobacter
convert vo, to No;

A:-Both A and R are true and R is the correct explanation of A
B:-Both A and R are true but Ris not the correct explanation of A