Download App

Evolution — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYEvolution4 Marks
Question
Show that Darwin’s natural selection is based on natural observation, with an example for each.
✓

Answer

  1. The resources of the nature are limited, so the size of population of a species is limited.
  2. The size of the population is fixed, except for some seasonal fluctuations.
  3. Each and every member of a population shows variation for every character.
  4. It is found in microbial or bacterial population growing in a culture that if everybody in a population reproduces to its maximum capacity, the population will grow exponentially.
  5. The population size in an ecosystem is limited–due to competition among individuals for limited resources and only those fit individuals utilise the resources at the cost of other to reproduce. Darwin suggested that nature creates some pressure on the population which eliminates some individuals and some better adapted ones survive. This natural pressure at each and every generation creates some small variation in a population, accumulation of which for many generations leads to origin of new species.

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 "4 Marks Questions" from Evolution→Evolution — all question types→BIOLOGY STD 12 Science question papers→Rajasthan Board STD 12 Science question papers→Rajasthan Board question paper generator→

Similar questions

“Phenylketonuria is a good example that explains Pleiotropy.” Justify.
→
Discuss the different barrier of innate immunity.
→
Explain the causes of Biodiversity loss?
→
Enlist the salient features of the double helix structure of DNA.
→
F1–generation does not resemble either of the parents.
→
Read the following and answer any four questions from (i) to (v) given below:
Apomixis is a mode of reproduction which does not involve formation of zygote through gametic fusion. In plants, apomixis commonly mimics sexual reproduction but produces seeds without fertilization. There are several methods of atomistic development in seeds. Thee two common ones are recurrent agamospermy and advective embryony.
  1. Apomixis is a type of reproduction in plants, in which?
  1. Fertilization does not take place.
  2. Male nucleus takes part in fertilization.
  3. Pollen fusion takes place.
  4. Generative nucleus takes part in fertilization.
  1. Which of the following statements is incorrect regarding recurrent agamospermy?
  1. It is the formation of seed that has an embryo formed without meiosis and syngamy.
  2. All the cells of embryo sac are diploid.
  3. An embryo develops directly from a diploid cell other than egg like that of nucleus and integument.
  4. None of these.
  1. Adventive embryony is found in:
  1. Citrus.
  2. Opuntia.
  3. Apple.
  4. Both (a) and (b).
  1. Formation of embryo directly from diploid egg without fertilization is called:
  1. Apospory.
  2. Diplospory.
  3. Polyembryony.
  4. Diploid parthenogenesis.
  1. If any somatic cell of sporophyte produces gametophyte without reduction division, it is called:
  1. Parthenogenesis.
  2. Apogamy.
  3. Apospory.
  4. Amphimixis.
→
Following is the sequence of nucleotide in two strands of DNA. Observe the strands and answer the preceding questions.
5' - GAATTC - 3'
3' - CTTAAG - 5'
  1. Name the special term used for such an arrangement of nucleotide.
  2. Name the special type of enzymes which work/ function at this specific points.
  3. Name the enzyme, that cut DNA between GA sequence.
  4. Name the single strands produced after the action of the enzyme.
→
Draw a diagrammatic sketch of biogas plant, and label its various components given below: Gas Holder, Sludge Chamber, Digester, Dung + water chamber.
→
Compare the characteristic features of insect pollinated and wind pollinated flowers. Explain how the respective features assist in pollination.
→
i. How are the characteristic features of pollen, anther and stigma of a maize plant suited for pollination by wind?
ii. How do you justify that:
1. Pollen grains are recovered from fossils?
2. Micropyle remains as a small pore in the seed coat of a fully developed seed?
→