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NCERT Exemplar · Class 12 · Biology

Chapter 13: Organisms and Populations

Practice each question, then open the answer or worked solution.

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LONG ANSWER TYPE QUESTIONS

12 questions
Q11Written answer

Does the light factor affect the distribution of organisms? Write a brief note giving suitable examples of either plants or animals.

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Worked solution

Yes, the light factor affects the distribution of organisms. Sunlight is an important factor for plants for their photosynthesis. For example, many species of small plants (herbs and shrubs) growing in forests are adapted to photosynthesize optimally under very low light conditions, so they will be seen distributed in shady areas under tall, canopied trees. The small plants in the forests are usually overshadowed by tall, canopied trees.

Q12Written answer

Give one example for each of the following:

i. Eurythermal plant species _______________

ii. A hot water spring organism _______________

iii. An organism seen in deep ocean trenches _______________

iv. An organism seen in compost pit _______________

v. A parasitic angiosperm _______________

vi. A stenothermal plant species _______________

vii. Soil organism _______________

viii. A benthic animal _______________

ix. Antifreeze compound seen in antarctic fish _______________

x. An organism which can conform _______________

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Worked solution

i. Eurythermal plant species – Mango, red algae, acacia

ii. A hot water spring organism – Thermus aquaticus, Archaebacteria

iii. An organism seen in deep ocean trenches – Jelly fishes, Sea cucumbers

iv. An organism seen in compost pit – Earthworm, fungi, bacteria

v. A parasitic angiosperm – Cuscuta reflexa

vi. A stenothermal plant species – Conifers, Cocosnucifera

vii. Soil organism – Bacteria, Earthworm

viii. A benthic animal – Crabs, sponges, Octopus

ix. Antifreeze compound seen in antarctic fish – Salt content, antifreeze glycoproteins or AFGPs

x. An organism which can conform – Frog

Plants, animals and fungi are all organisms which are part of the contiguous living system. Population, on the other hand, is simply a group of species that live in a well-defined geographical area. Some of the attributes of the population are population density, death rate and birth rate. The total number of individuals living in a particular niche of an area is called population density.

Important Concepts Covered in Chapter 13 Organisms and Populations

  1. Major Abiotic Factors
  2. Responses to Abiotic Factors
  3. Adaptations
  4. Populations
  5. Population Attributes
  6. Population Growth
  7. Life History Variation
  8. Population Interactions.

To learn more about NCERT Exemplar Class 12 Biology Chapter 13 Organisms and Populations, download the solutions in PDF and start practising.

The schools affiliated with CBSE are advised to follow the NCERT curriculum and textbooks. NCERT textbooks are one of the best study materials for the students of CBSE Class 12, which have all topics covered as per the latest CBSE syllabus (2023-24).

To score good marks in the board examination, students can solve the previous years’ question papers and sample papers, which will help them get familiar with the difficulty level of the questions and the marking scheme.