1. Acquired vs Inherited Traits:
Acquired: Developed during lifetime, NOT passed to offspring. Example: Muscular body from exercise.
Inherited: Present at birth, passed genetically. Example: Eye color, blood type.
2. Homozygous vs Heterozygous:
Homozygous: Both alleles same (TT or tt). True breeding.
Heterozygous: Different alleles (Tt). Shows dominant trait but carries recessive.
3. Dominant vs Recessive:
Dominant: Expresses even if one copy present (T).
Recessive: Expresses only when both copies present (tt). Hidden in heterozygous state.
4. Tall (Tt) × Tall (Tt):
TT : Tt : tt = 1:2:1 (genotype)
Tall : Dwarf = 3:1 (phenotype)
Probability of Dwarf = 25% (1/4)
5. Color Blind (carrier) mother × Normal father:
Mother: XCXc, Father: XCY
Sons: 50% color blind (XcY), 50% normal (XCY)
Daughters: All normal (50% carrier XCXc, 50% normal XCXC)
6. Blood Group (IAi × IBi):
Offspring: IAIB (AB), IAi (A), IBi (B), ii (O)
All blood groups possible in 1:1:1:1 ratio.
7. Why did Mendel choose pea plants? Easy to grow, short
life cycle, distinct contrasting traits, self-pollination (pure lines), cross-pollination possible, large
number of offspring.
8. Why is evolution not progress? Evolution is adaptation to
environment, not improvement. Simple organisms (bacteria) still exist. Complexity is not superior—survival
is the goal.
9. Why can't we determine sex at conception? Sex is
determined by sperm (X or Y) at fertilization, not visibly until later. Prenatal sex determination is
illegal in India to prevent female foeticide.
10. How do fossils provide evidence? Fossils in deeper
(older) layers are simpler. Shows gradual increase in complexity over time. Transitional forms (like
Archaeopteryx) link groups.
