Worksheets › Class 12 › Organisms and Populations
Class 12 Organisms and Populations worksheet
CBSE Biology. Adaptations, birth and death rates, density, exponential and logistic growth, interactions. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
Sample questions
Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.
Section A · multiple choice
- 1.
The interaction in which one species benefits and the other is unaffected is:
- amensalism
- parasitism
- mutualism
- commensalism
Answer
(d) commensalism
- 2.
The relationship in the sea anemone and the clown fish is:
- commensalism
- amensalism
- competition
- predation
Answer
(a) commensalism
signs: + and 0
- 3.
Which adaptation is shown by plants with CAM photosynthesis?
- Diapause, a stage of suspended development in unfavourable conditions
- A thick cuticle and stomata sunk in deep pits, which reduce water loss
- Getting water by oxidising its internal fat, and excreting very concentrated urine
- Stomata kept closed during the day
Answer
(d) Stomata kept closed during the day
Section B · short answer
- 4.
Distinguish between regulators and conformers.
Answer
Regulators maintain homeostasis by physiological and behavioural means, as birds and mammals keep a constant body temperature. Conformers cannot; their body temperature or osmotic concentration changes with the surroundings.
- 5.
(a) In a laboratory population of 150 fruit flies, 30 die in a week. Find the death rate. (b) 75 lotus plants gave 6 new plants in a year. Find the birth rate.
Answer
(a) 0.2 per fly per week; (b) 0.08 per lotus per year
30 ÷ 150; 6 ÷ 75
Section C · long answer
- 6.
Describe the ways organisms respond to stressful abiotic conditions.
Answer
Regulate: maintain homeostasis physiologically, as mammals keep body temperature constant by sweating or shivering. Conform: let the body change with the surroundings, as most animals and plants do. Migrate: move temporarily to a better area, as Siberian birds come to Bharatpur in winter. Suspend: bacteria, fungi and lower plants form thick-walled spores; seeds become dormant; bears hibernate; snails and fish aestivate; zooplankton enter diapause.
Fresh sheets for your child
In the app, every Organisms and Populations sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.
Coming soon for Android and iPhone.