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Organisms and Populations — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYOrganisms and Populations4 Marks
Question

  1. Which of the above represents the increase or decrease of population?
  2. If N is the population density at time t, then what would be its density at time (t + 1)? Give the formula.
  3. In a barn there were 30 rats. 5 more rats enter the barn and 6 out of the total rats were eaten by the cats. If 8 rats were born during the time period under consideration and 7 rats left the barn, find out the resultant population at time (t + 1).
  4. If a new habitat is just being colonized, out of the four factors affecting the population growth, which factor contributes the most?
✓

Answer

  1. a and d represents increase of population and b and c represent decrease of population.
  2. Nt+1 = Nt + [(B + I) - (D + E)]
  3. Here, Nt = 30;

I = 5; E = 7;

D = 6;

B = 8

Putting the value in Nt + 1

= Nt + [(B + I) - (D + E)] Nt + 1

= 30 + [(8 + 5) - (6 + 7)]

= 30 + [13 - 13]

= 30 + 0

= 30 rats.

  1. Immigration contributes the most.

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