Question

[5]
(a) Following are the responses of different animals to various abiotic factors. Describe each one with the help of an example.
(i) Regulate
(ii) Conform
(iii) Migrate
(iv) Suspend

(b) If 8 individuals in a population of 80 butterflies die in a week, calculate the death rate of population of butterflies during that period.

Answer 1

(a) (i) Regulate: Some organisms are able to maintain homeostasis by physiological or behavioural means, which ensures constant body temperature. All birds and mammals are capable of such regulation (thermoregulation and osmoregulation). [1]

(ii) Conform: Most animals and plants cannot maintain a constant internal temperature. Their body temperature changes with the surrounding temperature. In aquatic animals, the osmotic concentration of the body fluids changes according to the osmotic concentration of the water body. Example: Frogs and Polar bear. [1]

(iii) Migrate: Some organisms temporarily move away from the stressful habitat to a more hospitable area and return when the stressful period is over. For example, birds, during winter undertake long-distance migrations to more hospitable areas. Every winter, we see thousands of migratory birds coming from Siberia to Keolado National Park in Rajasthan. [1]

(iv) Suspend: In bacteria, fungi and lower plants, thick-walled spores are formed which help them to survive unfavourable conditions. In higher plants, seeds and some vegetative reproductive structures serve as means to cope up periods of stress as well as help them in dispersal. They do so by reducing their metabolic activity and going into a state of ‘dormancy’. Example: Fish, Snails. [1]


[1]
(b) Death rate is defined as the ratio of the number of deaths occurring in a population of a particular area during a particular period of time.
Death rate = $\frac{\text{Number of deaths}}{\text{Total populations}}$
Death rate = $\frac{8}{80}=0.1$ butterflies per week.