Mark an area of 1 m × 1 m in your school garden. Identify four organisms in this area, and count their numbers. Record the number of the organisms in Table 12.2. Table 12.2: Number of particular organisms at a given space and time Name of organism Population (Number of individual organisms) Plant 1

Mark the square with four sticks and string, then count every individual of each chosen kind inside it — counting a plant once even if it has many leaves, and not counting anything that is only half inside. Sample answer (one group's 1 m × 1 m plot in the school garden): Name of organism Population (number of individual organisms) Plant 1: Grass (doob) 20 Plant 2: Marigold 05 Animal 1: Ant 32 Animal 2: Earthworm 03 Then compile the data from all four or five groups, so that the class has counts from several squares. Why it happens: the size and the time are both fixed on purpose. A count only means something if you say how much area and when . Two groups counting different-sized patches, or counting ants at noon and at dusk, cannot compare their numbers at all. That is why a population is defined as a group of the same kind of organisms in a habitat at a given time .

NCERT Solutions for Class 8th Science Chapter 12 .2 Who All Live Together in Nature? — Activity 12.2: Let us record

Book page 19312 Updated on2026-09-19

Q1.

Mark an area of 1 m × 1 m in your school garden. Identify four organisms in this area, and count their numbers. Record the number of the organisms in Table 12.2.

Table 12.2: Number of particular organisms at a given space and time
Name of organism	Population (Number of individual organisms)
Plant 1 :	20
Plant 2 :	05
Animal 1 :
Animal 2 :

Table 12.2, page 193 — reproduced as printed; fill in the names and the two missing counts.

Answer

Mark the square with four sticks and string, then count every individual of each chosen kind inside it — counting a plant once even if it has many leaves, and not counting anything that is only half inside.

Sample answer (one group's 1 m × 1 m plot in the school garden):

Name of organism	Population (number of individual organisms)
Plant 1: Grass (doob)	20
Plant 2: Marigold	05
Animal 1: Ant	32
Animal 2: Earthworm	03

Then compile the data from all four or five groups, so that the class has counts from several squares.

Why it happens: the size and the time are both fixed on purpose. A count only means something if you say how much area and when. Two groups counting different-sized patches, or counting ants at noon and at dusk, cannot compare their numbers at all. That is why a population is defined as a group of the same kind of organisms in a habitat at a given time.

Q2.

In the given example, there is a population of 20 ______ plants and is only 5 ______ plants in the same 1 × 1 m2 area.

Answer

The blanks are for the names of the two kinds of plant you identified — Plant 1 and Plant 2 of your own table. With the sample counts above:

There is a population of 20 grass plants and only 5 marigold plants in the same 1 × 1 m² area.

Two different numbers, two different populations, one habitat.

Why it happens: the two plants are not equally common because they do not have equally good conditions. Grass spreads by runners and tolerates trampling and shade, so it fills the square; marigold has to grow from seed and needs more light and space, so far fewer of it fit in. Comparing populations in the same square is how you begin to see which conditions each kind of organism actually needs.

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