Download App

Organisms and Populations — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYOrganisms and Populations5 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. $N_t+1 = N_t + [(B + I) - (D + E)]$
  3. Here, $N_t= 30;$
$I = 5; E = 7;$

$D = 6;$

$B = 8$

Putting the value in $Nt + 1$

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

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

$= 30 + [13 - 13]$

$= 30 + 0$

$= 30$ rats.
  1. Immigration contributes the most.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "5 Marks Questions" from Organisms and Populations→Organisms and Populations — all question types→BIOLOGY STD 12 Science question papers→Gujarat Board STD 12 Science question papers→Gujarat Board question paper generator→

Similar questions

Explain the ovarian and uterine events that occur during a menstrual cycle in a human female, under the influence of Pituitary and Ovarian hormones respectively.
→
The following is the illustration of the sequence of ovarian events (a – i) in a human female.
What is the difference between “d” and “e” ?
→
Explain the process of budding with a suitable diagram. Also, explain its types.
→
If a desired gene is identified in an organism for some experiments, explain the process of the following:
  1. Cutting this desired gene at specific location.
  2. Synthesis of multiple copies of this desired gene.
→
Describe the roles of heat, primers and the bacterium Thermus aquaticus in the process of PCR.
→
Figure given below represent a certain technique of tissue culture.
  1. Name the technique, as shown in the diagram.
  2. What are the enzymes used to digest plant cell wall?
  3. Name the fusinogen.
  4. What is the product of fusion of protoplasts?
→
Why do some adolescents start taking drugs. How can this be avoided?
→
Describe in detail the development of female gametophyte in angiosperm with well labelled diagram.###Explain in the process of Megasporogenesis in a typical angiosperm plant by drawing the well labelled diagram of mature embryo sac.
→
In which categories have been classified the contraceptive methods. Describe any three methods in detail.
→
Haemophilia is a sex–linked recessive disease. Study the pedigree analysis given below showing the inheritance of the disease in a family and answer the questions that follow.
  1. Give the evidence from the above analysis which suggests that the disease is:
    1. Sex–linked and,
    2. Caused by a recessive allele.
  2. Write the possible genotypes of the individuals ‘2’ and ‘5’.
→