Download App

Heredity and Evolution — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceHeredity and Evolution5 Marks
Question
Explain with example how characteristics of a population changes over the years for the following situations:
  1. To gain survival advantage.
  2. Due to accidental survival.
  3. Temporary change of characteristics.
✓

Answer

  1. To gain survival advantage the best example is provided by peppered moth. When industrialization occurred in England the green coloured peppered moth who blended perfectly with the green lichen coloured trees were easily preyed upon by predators as the tree trunks became black due to soot covering. In order to survive these moths then changed their colour to grey and now blended perfectly with soot coated trees.
  2. Beetles have two colours either red or blue. It was seen that elephants crushed all red coloured beetle but not blue. Thus blue colour survives and hence this example shows accidental variation.
  3. Speciation of any plant or animal to the modern one is an example of temporary change of characteristics so as to bring about a finally best suited 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 "[5 marks 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

The transport system in plants consists of two kinds of tissues X and Y. The tissue X is made up of living cells and consists of two components A and B. The component A has tiny pores in its end walls and contains only cytoplasm but no nucleus. On the other hand, component B has cytoplasm as well as nucleus. The tissue Y is made up of dead cells and consists of two components C and D. The component C has open ends whereas component D does not have open ends. In flowering plants, either only C or both C and D transport water but D is the only water conducting tissue in non - flowering plants.
  1. What is (i) tissue X, (ii) component A and (iii) component B?
  2. What is (i) tissue Y, (ii) component C and (iii) component D?
→
What are the methods used by plants to get rid of their waste products?
→
What is an electromagnet? Describe the construction and working of an electromagnet with the help of a labelled diagram.
→
Distinguish between pollination and fertilisation. Mention the site and product of fertilisation in a flower.
Draw a neat, labelled diagram of a pistil showing pollen tube growth and its entry into the ovule.
→
There were lot of organisms A in the crop fields in an area. These organisms used to feed on organisms B also present in the crop fields but which damaged the standing crops. One day some people arrived in the fields and killed all the organisms A so that they could remove their C for making fancy items which were in great demand. Due to large scale killing of A, the population of B increased too much damaging all the crops in the area and causing a famine-like situation. Apart from A, there is another organism D which can also kill and eat B. Name A, B, C and D.
→
Two resistors, with resistances $ 5 Ω$ and $10 Ω$ respectively are to be connected to a battery of emf 6V so as to obtain:
  1. Minimum current flowing.
  2. Maximum current flowing.
  1. How will you connect the resistances in each case?
  2. Calculate the strength of the total current in the circuit in the two cases.
→
Draw a pond ecosystem showing its different components.
→
How would you bring about the following conversions? Name the process and write the reaction involved.
  1. Ethanol to ethene.
  2. Propanol to propanoic acid. Write the reactions.
→
Give reasons why a woman should avoid frequent pregnancies. Explain the following methods of contraception giving one example of each.
  1. Barrier method.
  2. Chemical method.
→
A person buys two electrical devices P and Q for lighting purposes in his house. The device P consumes only 5 units of electricity in a month but device Q consumes 15 units of electricity in a month when used for the same number of hours daily. The device Q wastes a lot of electricity by radiating energy C but P does not do so.
  1. What type of device is (i) P, and (ii) Q?
  2. Name one component which is present in Q but not in P.
  3. Name the energy C.
  4. Which device is more energy efficient: P or Q?
  5. Which fossil fuel is most likely to be conserved if all of us switch over to devices like P?
→