1. Why are traits acquired during lifetime not inherited?
Acquired traits affect somatic (body) cells, not germ (reproductive) cells. Only changes in DNA of gametes
(mutations) are passed on.
2. Why is variation beneficial? Variations provide raw
material for natural selection. Some variants survive better in changed conditions, ensuring species
survival.
3. Does evolution mean human evolved from monkeys? NO.
Humans and modern apes share a common ancestor. We evolved separately from that ancestor—we are cousins, not
parent-child.
4. Why are all humans one species despite differences? We
can interbreed and produce fertile offspring. Physical differences (skin color, height) are minor variations
within the same gene pool.
5. What happened to peppered moths? Before industrial
revolution: Most moths were light (camouflaged on lichen-covered trees). After pollution: Lichens died,
trees blackened → Dark moths survived better (natural selection shifted population).
6. What does this show? Natural selection acts on existing
variation. Environment determines which variants are "fittest." This is evolution in action, observable in
short time.
7. After clean air acts? Trees became cleaner again. Light
moths regained advantage. Population shifted back to more light moths. Shows evolution is not directional—it
responds to environment.
8. Where did humans originate? Africa. Fossil evidence and
DNA studies both point to African origin. From there, humans migrated to other continents.
9. Why are humans from different continents more alike than
different? Human migration out of Africa was recent (~100,000 years ago). Not enough time for
major genetic differences. All humans are 99.9% genetically identical.
10. What is molecular phylogeny? Using DNA/protein sequences
to trace evolutionary relationships. More similar DNA = more recent common ancestor. Example: Humans share
98%+ DNA with chimpanzees.
11. Assertion: Two parents cannot produce identical
offspring (except identical twins).
Reason: Sexual reproduction involves meiosis (random assortment) and fertilization (random
gamete combination), creating unique combinations every time.
Both A and R are True, R is correct explanation of A.
12. Can evolution go backward? No. Evolution is not
reversible. Once a species goes extinct, it cannot return. However, similar adaptations can re-evolve in
different lineages (convergent evolution).
