Organisms and Populations

Previous Years' CBSE Board Questions

11.1 Populations

Population: Attributes and Growth

MCO

Important attributes belonging to a population but not to an individual are

1. birth rate and death rate
2. male and female

.<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1

6000

1. birth and death
2. sex-ratio. 4000 ੂੰ<br>2000
3. (i) only (b) (ii) only 1900 1920 1940 1960 1980 Year

Select the correct option from the given options.

1. (ii) and (iii) (d) (i) and (iv) (2023) U

V5A (1 mark)

1. Construct an age pyramid which reflects an expanding growth status of human population.

52000<br>1500 В

1000<br>500

1960 1970 1980 1990 2000 2010

Year

(Al 2014) Cr

SAI (2 marks)

1. List and explain any two factors that lead to a decrease in the population density of an area.

(2023) R

1. As per a recent newspaper report, a particular country showed declining population growth rate. According to you, what could be the two most possible reasons for this decline and why?

(Term II, 2021-22) Ap

Immigration

1. В Population D →(A)

Emigration

Observe the schematic representation given above and answer the following questions:

1. Identify A and B.
2. Calculate the growth rate of bacteria in a curd sample, where 1 million bacteria increased to two million, within a period of one hour.

(Term II, 2021-22)

Identify the type of pyramid given above. Write

the identifying feature on the basis of which you

identified it. (Term II, 2021-22)

The graph given below, A and B, represent population

of elephants in two different National Parks (a

hypothetical situation) at different times.

Study the graphs and comment upon the pattern of

growth observed. Mention the possible reason for

such patterns seen in nature. (Term II, 2021-22) [Ap.

What would be the best method to measure the total

population density of the number of fishes in river

and why? (Term II, 2021-22) U

(a) How will you measure population density of fish

in a lake?

(b) In a pond, there are 100 frogs. 20 more were

born in a year. Calculate the birth rate of this

population. (2019)

If 8 individuals in a population of 80 butterflies die

in a week, calculate the death rate of population of

butterflies during that period. (2/5, 2018) (4)

1. Construct an age pyramid which reflects a stable growth status of human population. (Delhi 2014)
2. Explain Verhulst-Pearl logistic growth of a population. (Foreign 2014)

SA II (3 marks)

1. Post-Reproductive
2. The population of a metro city experiences fluctuations in its population density over a period of time.

Reproductive

1. to increase?

Pre-Reproductive

1. When does the population in a metro city tend to decline?
2. If N is the population density at time 't', write the population density at time 't + 1'.

Population Density (N) (2020) Ap Population density (N) Time (t) 14. D

Study the schematic representation given above and answer the following questions.

1. Identify A in it.
2. Identify B in it.
3. When population density at time t is N as shown above, write the population density at time t + 1 in the form of an equation using appropriate symbols. (2020)
4. Study the age pyramids 'A', 'B' and 'C' of the human population given below and answer the questions that follow:

Post-reproductive

Reproductive

Pre-reproductive

1. (B) (C)

1. Identify pyramids 'B' and 'C'.
2. Write the basis on which the above pyramids are plotted. (2020)

Study the graph given below showing the different types of growth curves of different species.

<math>\frac{dN}{r} = rN</math> a К

Population density (N) <math>\frac{dN}{dr} = rN'</math> Time (t)—-> ΩĹ. opulation density (N) Time (t) →

Answer the questions:

1. Name the type of growth curve 'a' shown in the graph.
2. State one reason why the growth curve 'b' is said to be logistic.
3. What is 'K' representing in the equation <math>\frac{dN}{dt} = rN \left[ \frac{K - N}{K} \right]</math> given along the logistic curve.
4. Study the graph given below and answer the questions that follow:
5. The curve 'b' is described by the following equation:

<math>\frac{dN}{dt} = rN \left\{ \frac{K - N}{K} \right\}</math>

What does 'K' stand for in this equation?

Mention its significance.

1. Which one of the two curves is considered a more realistic one for most of the animal populations?
2. Which curve would depict the population of a species of deer if there are no predators in the habitat? Why is it so? (Al 2019)
3. Differentiate between an 'Expanding age pyramid' and a 'Stable age pyramid'. Substantiate your answer with diagrams. (2019)
4. (a) Name the two growth models that represent population growth and draw the respective growth curves they represent.
5. State the basis for the difference in the shape of these curves.
6. Which one of the curves represent the human population growth at present? Do you think such a curve is sustainable? Give reason in support of your answer. (Al 2016)
7. Study the graph given below and answer the questions that follow.
8. Write the status of food and space in the curves A and B.
9. In the absence of predators, which one of the two curves would appropriately depict the prey population?

(2020C)