1.Zygote formation during lateral conjugation in spirogyra is different from zygote formation in the gametophyte stage of fern plants in:
1 mark
AThe main method of reproduction used
Why this is wrongBoth are examples of sexual reproduction, so the main method of reproduction is not the point of difference.
BNumber of chromosomes sets in zygote
Why this is wrongBoth zygotes are diploid (two chromosome sets), so this is not where they differ.
CType of cells participated Correct answer
DGenetic diversity
Why this is wrongBoth fusions combine genetic material and give variation, so genetic diversity is not the distinguishing difference asked for.
Why this is correctSpirogyra conjugation uses undifferentiated cells, while fern fertilization uses specialized gametes.
In Spirogyra, lateral conjugation fuses two ordinary vegetative cells of adjacent filaments, which act as gametes; in the fern's gametophyte stage the zygote forms from specialised, differentiated gametes — an egg and a sperm. Both zygotes are diploid, so the number of chromosome sets is the same; the real difference is the type of cells that take part in forming the zygote.
2.Which of the following factors does not directly affect the success of the pollination process in the flower ?
1 mark
ANumber of ovules Correct answer
BInsects
Why this is wrongInsects act as pollination vectors that carry pollen between flowers, so they directly affect pollination success.
CStigma shape
Why this is wrongStigma shape determines whether pollen can land and adhere, so it directly affects pollination success.
DWind
Why this is wrongWind is a pollen-dispersal agent for many flowers, so it directly affects pollination success.
Why this is correctPollination is transfer of pollen to stigma, so ovule number affects later seed formation, not pollination success directly.
Pollination is the transfer of pollen grains from the anther to the stigma of the same or another flower. Its success depends on agents that carry the pollen, such as wind and insects, and on the shape and receptivity of the stigma, which lets pollen land and adhere. The number of ovules concerns how many seeds can later form inside the ovary, which is a matter of fertilization that happens after pollination, not a direct factor in pollen reaching the stigma. Method: ask whether each factor helps pollen reach or land on the stigma; if it does not, it does not directly affect pollination.
3.What is the number of fruits formed by a flower its ovary consists of 10 carpels?
1 mark
AOne fruit Correct answer
B5 fruits
Why this is wrong5 fruits has no biological basis; the carpels do not split the single ovary into half-fruits.
C10 fruits
Why this is wrong10 fruits wrongly assumes each carpel becomes a fruit, but carpels are parts of one ovary, not separate ovaries.
DNumber of fruits equal the number of ovules in the carpels
Why this is wrongThe number of fruits never equals the number of ovules; ovules develop into seeds inside the one fruit, not into separate fruits.
Why this is correctA single flower ovary develops into one fruit even if it contains several carpels.
The rule being tested is that one whole flower has one ovary, and after fertilization that single ovary ripens into one fruit — no matter how many carpels are fused inside it. The 10 carpels are just the structural units (each holding ovules) within that one ovary; they do not each become a separate fruit. So the number of fruits follows the number of ovaries (one flower = one ovary = one fruit), while the number of ovules predicts the number of seeds inside. Carry this with you: count ovaries to count fruits, count ovules to count seeds.