Download App

Evolution — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYEvolution5 Marks
Question
State and explain any three factors affecting allele frequency in populations.
✓

Answer

Following are the three out of five factors which affect allele frequency in populations:
  1. Genetic Drift: The change in the frequency of a gene variant in a population due to random sampling is called genetic drift. Genetic drift may cause a gene variant to disappear completely and result in reduced genetic variation.
  2. Genetic Recombination: Production of offspring with traits which differ from parents is called genetic recombination.
  3. Natural Selection: This theory is based on the premise that nature selects only those traits which help an organism to survive in the changed conditions. Natural selection leads to survival of the fittest. Those which are not fit to survive perish in the long run; paving the way for evolution of a 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 "5 Marks Questions" from Evolution→Evolution — all question types→BIOLOGY STD 12 Science question papers→Gujarat Board STD 12 Science question papers→Gujarat Board question paper generator→

Similar questions

A.
(i) Why is there a need to conserve biodiversity? (Any two reasons)
(ii) Name and explain any two causes that are responsible for the loss of biodiversity.
→
How bacterial cells are made competent to take up DNA?
→
(i) Write the name of the disease occurring as a result of point mutation.
(ii) Explain the lac operon.
(iii) Draw a labelled diagram of the lac operon.
→
Describe the various evidences from palaeontology which support organic evolution.
→
In a pond, we see plants which are free-floating; rooted–submerged; rooted emergent; rooted with floating leaves. Write the type of plants against each of them.
 
Plant Name
Type
a.
Hydrilla
____________
b.
Typha
____________
c.
Nymphaea
____________
d.
Lemna
____________
e.
Vallisnaria
____________
→
Write the type and location of the gene causing thalassemia in humans. State the cause and symptoms of the disease. How is sickle cell anaemia different from this disease?
→
Answer the following questions:
Name the hormones secreted and write their functions:
  1. By corpus luteum and placenta (any two) .
  2. During Follicular phase and parturition.
→
Enumerate the points that have to be considered for successful bee-keeping.
→
What is somatic hybridisation? Explain the various steps involved in the process. Mention any two uses of somatic hybridisation.
→
A person in your colony has recently been diagnosed with AIDS. People/residents in the colony want him to leave the colony for the fear of spread of AIDS.
  1. Write your view on the situation, giving reasons.
  2. List the possible preventive measures that you would suggest to the residents of your locality in a meeting organised by you so that they understand the situation.
  3. Write the symptoms and the causative agent of AIDS.
→