Download App

Heredity and Evolution — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceHeredity and Evolution3 Marks
Question
Explain the terms:
  1. Speciation.
  2. Natural selection.
✓

Answer

SPECIATION: A species may be defined as a group of organization capable of interbreeding and producing fertile off springs. The process of formation of new species from existing one by evolutionary means is known as speciation.
Natural selection: According to Darwin's theory of evolution., natural selection may be defined as the process by which the organisms which are better adaptive to a particular kind of environment tends to survive, leading in the elimination of the organism less adaptive to that environment.

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 "[3 Mark Questions]" from Heredity and Evolution→Heredity and Evolution — all question types→Science STD 10 question papers→CBSE Board STD 10 question papers→CBSE Board question paper generator→

Similar questions

List any two modes of asexual reproduction in animals. Under which mode of reproduction is vegetative propagation placed and why? List two advantages of vegetative propagation.
→
Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.
→
‘‘A trait may be inherited, but may not be expressed.’’ Justify this statement with the help of a suitable example.
→
A magnesium ribbon is burnt in oxygen to give a white compound X accompanied by emission of light. If the burning ribbon is now placed in an atmosphere of nitrogen, it continues to burn and forms a compound Y.
  1. Write the chemical formulae of X and Y.
  2. Write a balanced chemical equation, when X is dissolved in water.
→
In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is formed as by product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y giving the chemical equation of the reactions involved.
→
Some of the important fossils which have been studied are those of organisms X, Y and Z. X were marine arthropods which were common between 400 to 600 million years ago. Y were the invertebrate animals (molluscs) with a flat, coiled, spiral shell which lived in the sea about 180 million years ago. Z are the extinct carnivorous or herbivorous reptiles which appeared on the earth about 250 million years ago and became extinct about 65 million years ago. What are X, Y and Z?
→
The magnification of an image formed by a lens is – 1. If the distance of the image from the optical centre of the lens is 35 cm, where is the object placed ? What is the nature and focal length of the lens? If the object is displaced 20 cm towards the optical centre of the lens, where would the image be formed and what will be its nature? Draw a ray diagram to justify your answer.
→
What is DNA copying? State its importance.
→
Generally, when metals are treated with mineral acids, hydrogen gas is liberated but when metals (except Mn and Mg ), treated with $HNO _3$, hydrogen is not liberated, why?
→
What happens when hydrogen gas is added to copper oxide?
→