Question

(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 a population of butterflies during that period.

Answer 1

(a) The responses of different animals to various abiotic factors are:

(i) Regulate- Control or maintain the rate or speed of a process so that it operates properly. Some organisms are able to maintain homeostasis by physiological means which ensures constant body temperature, constant osmotic concentration, etc. This is called regulation. Example- All birds and mammals, and a very few lower vertebrate and invertebrate species are capable of regulation (thermoregulation and osmoregulation). Plants, on the other hand, do not have such mechanisms to maintain internal temperatures.

(ii) Conform- Agree or comply to set standards or conventions. A majority (99 percent) of animals and nearly all plants cannot maintain a constant internal environment. Their body temperature changes with the ambient temperature. In aquatic animals, the osmotic concentration of the body fluids changes with that of the ambient water osmotic concentration. These animals and plants are simply conformers. Some species have evolved the ability to regulate, but only over a limited range of environmental conditions, beyond which they simply conform.

(iii) Migrate- Movement from one region or habitat to another according to the seasons. The organism can move away temporarily from the stressful habitat to a more hospitable area and return when a stressful period is over. Example- Many animals, particularly birds, during winter undertake long-distance migrations to more hospitable areas.

(iv) Suspend- Temporarily prevent from continuing or being in effect. In bacteria, fungi and lower plants, various kinds of thick-walled spores are formed which help them to survive unfavorable conditions – these germinate on the availability of suitable environment. In higher plants, seeds and some other vegetative reproductive structures serve as means to tide over periods of stress besides helping in dispersal. They germinate to form new plants under favorable moisture and temperature conditions. They do so by reducing their metabolic activity and going into a state of ‘dormancy’.

(b) Death rate or mortality rate is the number of deaths per 1000 individuals of a population per year.

Hence, if 8 individuals in a population of 80 butterflies die in a week

Death rate= 8/80 = 0.1

The death rate of the population of butterflies during that period is 0.1