Which one of the following is categorised as a parasite in the true sense?
Human foetus developing inside the uterus draws nourishment from the mother
Head louse living on the human scalp as well as laying eggs on human hair
The cuckoo (koel) lays its eggs in crow's nest
The cuckoo (koel) lays its eggs in crow's nest
B.
Head louse living on the human scalp as well as laying eggs on human hair
Human louse (pediculus) lives among hair and surface of human body feeding on blood. It spreads diseases like typhus.
Consider the following statements (I) - (IV) each with one or two blanks.
I. Bears go into ..... (1) .... during winter to .......(2) ..... cold weather.
II. A conical age pyramid with a broad base represents ......(3) ....... human population.
III. A wasp pollinating a fig flower is an example of ........ (4) ..........
IV. An area with high levels of species richness is known as ........ (5) .......
Which one of the following options give the correct fill up the respective blanks numbers from (1) to (5) in the statements.
(2) stable, (4) commensalism, (5) marsh
(1) aestivation, (5) escape, (3) stable, (4) mutualism
(3) expanding, (4) commensalism, (5) biodiversity park
(3) expanding, (4) commensalism, (5) biodiversity park
D.
(3) expanding, (4) commensalism, (5) biodiversity park
Bears go into hibernation during winter t o escape the cold weather.
A conical age pyramid with a broad base represents expanding the human population.
A wasp pollinating a fig flower is an example of mutualism.
An area with high levels of species richness is known as hot spots.
What type of human population is represented by the following age pyramid? 
Stable population
Declining Population
Expanding population
Expanding population
B.
Declining Population
An age pyramid is a graphic representation of the proportion of various age groups of a population with pre-reproductive at the reproduction in the middle and posts-reproductive at the top. For human population, the age pyramids show age distribution of males and females in the combined diagram. The shape of the age pyramids reflects the growth status of the population. In a declining population the shape of the pyramid is urn- shaped.
Consider the following four conditions (a - d) and select the correct pair of them as adaptation to environment in desert lizards.
The conditions:
I. Burrowing in soil to escape high temperature.
II. Losing heat rapidly from the body during high temperature
III. Bask in sun when temperature is low
IV. Insulating body due to thick fatty dermis
I and III
II and IV
I and II
I and II
A.
I and III
Some organisms show behavioural responses to cope with variations in their environment. Desert lizzards bask in the sun and absorb heat when their body temperature drops below the comfort zone, but move into shade when the ambient temperature starts increasing. Some species are capable of burrowing into the soil to hide and escape from the above-ground heat.
The logistic population growth is expressed by the equation
dN/dt = rN
dN/dt = rN
B.
A population growing in a habitat with limited resources show initially a lag phase, followed by phases of acceleration and deceleration and finally an asymptote when the population density reaches the carrying capacity. A plot of N (population density at time t) in relation to time (t) results in the sigmoid curve. This type of population grown is called Verhulst -pearl Logistic Growth and is describes by the following equation:
where N = population density at time t,
r = Intrinsic rate of natural increase
K = carrying capacity
Since resources for growth for most animal populations are finite and become limiting sooner or later, the logistic growth model is considered a more realistic one.
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