Download App

Organisms and Populations — BIOLOGY STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 ScienceBIOLOGYOrganisms and Populations1 Mark
Question
For question two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both assertion and reason are true and reason is the correct explanation of assertion.
  2. Both assertion and reason are true but reason is not the correct explanation of assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false.
Assertion: Biotic potential is realised only when the environmental conditions are limiting.
Reason: Under such conditions only, the population size can increase at the maximum rate.
✓

Answer

  1. Both assertion and reason are false.

Explanation:

The inherent maximum capacity of an organism to reproduce or increase in number is termed as biotic potential (designated by the symbol 'r). Biotic potential is realised only when the environmental conditions are non-limiting, so that natality rate (birth - rate) is maximum and mortality rate (death - rate) is minimum. Under these conditions, population size increases at the maximum rate. However, nature keeps a check on the expression of biotic potential. For example, if a pair of flies is allowed to reproduce unchecked, the fly population may outweigh the earth in a few years. The environmental check on population size, or its biotic potential is called environmental resistance. With increase in population size, the environmental resistance (against the population) tends to increase. The environmental resistance represents the limiting effect of abiotic (e.g., water, space) and biotic factors (e.g., food, competition) that do not allow organisms to attain their biotic potential and keep the population size at a much lower level.

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 "Assertion (A) & Reason (B) MCQ" from Organisms and Populations→Organisms and Populations — all question types→BIOLOGY STD 12 Science question papers→Bihar Board STD 12 Science question papers→Bihar Board question paper generator→

Similar questions

For question two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both assertion and reason are true and reason is the correct explanation of assertion.
  2. Both assertion and reason are true but reason is not the correct explanation of assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false.
Assertion : Some diseases that attack in childhood do not attack again.
Reason: Memory cells plays an important role.
→
For question, two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
  2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
  3. Assertion is true, but reason is false.
  4. Both assertion and reason are false.
Assertion : Smoking causes oxygen deficiency in the body.
Reason: Carbon monoxide, when inhaled while smoking, combines with haemoglobin to form chemically stable compound.
→
Directions: In the following questions, the Assertions (A) and Reason(s) (R) have been put forward. Read both the statements carefully and choose the correct alternative from the following:
Assertion: Recognition site should be preferably single and responsive to commonly used restriction enzyme.
Reason: In pBR 322 alien DNA is ligated generally in the area of Bam - HI site of tetracycline resistance gene.
  1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion.
  2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion.
  3. If the assertion is true but the reason is false.
  4. If both the assertion and reason are false.
  5. If the assertion is false but reason is true.
→
For question, two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
  2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
  3. Assertion is true, but reason is false.
  4. Both assertion and reason are false.
Assertion :Mucous membrane immobilises the micro-organisms in the body

Reason: Microorganisms and dust particles entering the respiratory tract are trapped in the mucus.

→
For question two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both assertion and reason are true and reason is the correct explanation of assertion.
  2. Both assertion and reason are true but reason is not the correct explanation of assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false.
Assertion : Linked gene show dihybrid ratio of 9 : 3 : 3 : 1.
Reason: Linked gene undergo independent assortment.
→
Assertion (A): Escherichia coli, Shigella sp., and Salmonella sp. are all responsible for diarrhoeal diseases.
Reason (R): Dehydration is common to all types of diarrhoeal diseases and an adequate supply of fluids and electrolytes should be ensured.
→
For two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
  2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
  3. Assertion is true, but reason is false.
  4. Both assertion and reason are false.
Assertion: The endometrium undergoes cyclical changes during menstrual cycle.
Reason: The myometrium exhibits strong contractions during delivery of the baby.
→
Assertion (A): Fossils are remains of dead organisms.
Reason (R): Palaeontology is helpful in study of evolution.
→
For two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
  2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
  3. Assertion is true, but reason is false.
  4. Both assertion and reason are false.
Assertion: Ubisch bodies are produced by glandular tape tum.
Reason: Ubisch bodies participated in the thickening of exine.
→
For question two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both assertion and reason are true and reason is the correct explanation of assertion.
  2. Both assertion and reason are true but reason is not the correct explanation of assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false.
Assertion: Epistasis does not show normal dihybrid ratio, i.e., 9 : 3 : 3 : 1.
Reason: A gene suppresses the phenotypic expression of a non-allelic gene.
→