Download App

Evolution — BIOLOGY STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 ScienceBIOLOGYEvolution5 Marks
Question
  1. Explain Darwinian theory of evolution with the help of one suitable example.
  2. State the two key concepts of the theory.
  3. Amongst pea tendril, Opuntia spines, lemon thorn and Cucurbita tendrils, which ones are homologous structures. Why do you call them so?
✓

Answer

  1. Any population has built in variation for every character.

Individuals with those characters which enable them to survive better in the given environment, would outbreed the others, who are less adapted. Fitness, according to Darwin, is reproductive fitness, i.e. individuals who are more fit in an environment leave more progeny than others.

These progenies survive better and more and more fit individuals are added to the population, i.e. natural selection.

The population thus comes to possess more fit individuals, i.e. nature selects the better fit invididuals and over a long period of time, through a number of generations, the population slowly becomes modified into a different form or a species, in the process called evolution, e.g. evolution of DDT-resistant mosquitoes.

  1. The two key concepts of Darwinian theory are:
  • Branching descent.
  • Natural selection.
  1.  
  • Lemon thorn and Cucurbita tendrils are homologous-as both are stem modified
  • Opuntia spines and pea tendrils are homologousas both are leaf modifications.
  • Homologous organs are those organs in different groups of organisms, that are similar in basic structural and developmental patterns, but perform different functions and are superficially distinct.

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 "Long Answer Type Questions [5M]" from Evolution→Evolution — all question types→BIOLOGY STD 12 Science question papers→Bihar Board STD 12 Science question papers→Bihar Board question paper generator→

Similar questions

  1. How does a chromosomal disorder differ from a Mendelian disorder?
  2. Name any two chromosomal aberration associated disorders.
  3. List the characteristics of the disorders mentioned above that help in their diagnosis.
→
Using various resources such as your school Library or the internet and discussions with your teacher, trace the evolutionary stages of any one animal say horse.
→
Draw a diagram and briefly describe the life cycle of Plasmodium.###Make a labeled diagram and briefly describe the various stages of the life cycle of Plasmodium.
→
The biology teacher asked her students to verify the experiment on transformation principle in bacteria to establish DNA as genetic material. The class was divided into two groups. The teacher asked them to submit the reports. Group 2 did not use mouse and did not repeat Griffith's experiment. The teacher praised them.
  1. Which experiment did they perform?
  2. Explain the experiment in brief.
  3. Who and when performed the transformation principle experiment?
  4. What values did students of group 2 exhibit?
→
Write notes on ex-situ conservation of biodiversity
→
Why are sedimentary cycles slower than gaseous cycles? Explain giving resons.
→
Match the items in Column I with those in Column II.
S.No.
Column I
S.No.
Column II
(A)
Pyramid of energy
(i)
Phytoplanktons
(B)
Pyramid of biomass
(ii)
Mesic forest
(C)
Climax community
(iii)
Upright/ inverted
(D)
Hydrarch succession
(iv)
Alwayes upright
 
 
(v)
Pioneer species
→
What are ecological pyramids? Mention its limitations.
→
Explain the law of dominance by Punnet Square method.
→
Name and describe the steps involved in the technique widely used in forensics that serves as the basis of paternity testing in case of disputes.
→