11 Questions with Answers and Explanations on Growth of Human Population for Biology Students:
1. In India, human population is heavily weighted towards the younger age groups as a result of
(a) short life span of many individuals and high birth rate
Image Source: static.squarespace.com
ADVERTISEMENTS:
(b) long life span of many individuals and high birth rate
(c) short life span of many individuals and low birth rate
(d) long life span of many individuals and low birth rate.
ADVERTISEMENTS:
Answer and Explanation:
1. (a): A population having mostly younger age group means its birth rate is high. If death rate is increased then the proportion of old age group will be increased. But in this case death rate has increasing trend thence in a human population which is heavily weighted towards the younger age groups; there will be short life span and high birth rate.
2. The concept that ‘population tends to increase geometrically while food supply increases arithmetically’ was put forward by
(a) Thomas Malthus
ADVERTISEMENTS:
(b) Charles Darwin
(c) Stuart Mill
(d) Adam Smith.
Answer and Explanation:
2. (a): In 1798 T. R. Malthus, a British economist, put forward a theory of human population growth, (i) He, stated that population grows geometrically when unchecked, whereas the means of its subsistence like food grow only arithmetically, (ii) Naturally, after some time an imbalance would occur in the population and the environment, (iii) When the imbalance reaches a certain value, some factors like hunger, epidemics, floods, earthquakes, war, etc. will bring the population to a desired level. Such a population “crash” is called catastrophic control of population. These factors were called “Positive checks” by Malthus.
3. What is the most important factor for the success of animal population?
(a) adaptability
(b) inter-species activity
(c) natality
(d) unlimited food.
Answer and Explanation:
3. (a): Adaptations may be morphological involving shape, size and external features of the living organisms or anatomical including adaptive modifications in the visceral organs. These adaptations are mostly due to the effect of environment (both a biotic and biotic) in which the organisms reside. Based upon the habits and habitats met within the present organisms, Mathew has classified adaptations into the following categories.
(i) Cursorial adaptations or speed adaptations for running.
(ii) Fossorial adaptations or adaptations for burrowing.
(iii) Scansorial (arboreal) adaptations or adaptations for climbing.
(iv) Volent adaptations or adaptations for flight.
(v) Cave adaptations
(vi) Desert adaptations
(vii) Aquatic adaptations.
4. The present population of the world is about
(a) 15 trillion
(b) 6 billion
(c) 500 million
(d) 100 million.
Answer and Explanation:
4. (b): As this question appeared in 1997, so the population of world in mid 1997 was 5, 840, 324, 240 i.e. approximately 6 billion.
5. Two opposite forces operate in the growth and development of every population. One of them is related to the ability to reproduce at a given rate. The force opposite to it is called
(a) fecundity
(b) environmental resistances
(c) biotic control
(d) mortality.
Answer and Explanation:
5. (b): The environmental factors which can check the growth of population size constitute the environmental resistance. These include predators, food, water, nesting sites, similar competitors, etc. All living things tend to reproduce until the point at which their environment becomes a limiting factor. No population, human or otherwise, can grow indefinitely; eventually, some biotic or a biotic variable will begin to limit population growth.
6. The most important component of the oral contraceptive pills is
(a) thyroxine
(b) luteinizing hormont
(c) progesterone
(d) growth hormone.
Answer and Explanation:
6. (c): The most common type of pill is the so called “combined pill”. It contains a combination of synthetic progestins (acting like progesterone) and estrogen. Combined pills inhibit ovulation by inhibiting the normal release of FSH and LH from the pituitary. They mimic the hormones produced by the corpus luteum, causing the uterine walls to thicken, as during normal menstrual cycle, and suppressing the release of FSH and LH.
7. Tablets to prevent male contraception contain
(a) progesterone
(b) LH
(c) FSH
(d) both (b) and (c).
Answer and Explanation:
7. (d): Male contraceptives work by interfering with sperm production or delivery, that means they inhibit the spermatogenesis as well as the function of male sex hormone testosterone.
LH and FSH (both called gonadotropic hormone are secreted from anterior pituitary) have specific functions in the testis. FSH stimulates male germ cells for spermatogenesis and LH stimulates accessory cells, called leydig cells to produce sex steroids, especially testosterone. Thus, these two hormones (FSH and LH) prevent male contraception.
8. What is the work of copper-T?
(a) to inhibit ovulation
(b) to inhibit fertilization
(c) to inhibit implantation of blast cyst
(d) to inhibit gametogenesis.
Answer and Explanation:
8. (b & c): Copper-T is an intrauterine device (IUD) used by women as a birth control. An IUD is a small device which is placed inside the uterus. The vertical and horizontal arms of the Copper – T contain copper which is slowly released into the uterine cavity. Copper stops sperm from making their way up through the uterus into the tubes, and it reduces the ability of sperm to fertilize the egg. It also prevents a fertilized egg (blast cyst) from successfully implanting in the lining of the uterus if fertilization has occurred.
9. What is the work of progesterone which is present in oral contraceptive pills?
(a) to inhibit ovulation
(b) to check oogenesis
(c) to check entry of sperms into cervix and to make them inactive
(d) to check sexual behaviour.
Answer and Explanation:
9. (a): Refer answer 6.
10. In a population, unrestricted reproductive capacity is called as
(a) biotic potential
(b) fertility rate
(c) carrying capacity
(d) birth rate.
Answer and Explanation:
10. (a): Biotic potential is defined as the physiological capacity of organisms to produce their offspring under natural conditions. It is also called reproductive potential. In nature, the biotic potential of organisms is enormous but all the organisms do not survive due to the lack of food and space. There are also a number of diseases and the predatory organisms that feed upon other organisms. The carrying capacity is the maximum number of individuals which the environment can support or sustain. Birth rate is the number of off springs produced per female per unit time. Fertility rate is the number of live births occurring in a year per 1000 women of child-bearing age (usually 15 to 44 years).
11. The formula for exponential population growth is
(a) dN/dt = rN
(b) dt/dN = rN
(c) dN/rN = dt
(d) rN/dN = dt
Answer and Explanation:
11. (a): Nearly all populations will tend to grow exponentially as long as there are resources available. The formula for exponential population growth is dN/dt – rN. In this equation d is the rate of change, A’is I the number of existing individuals, r is the intrinsic growth rate, I is time, and dN/dt is the rate of change in population size.