Okay I have two more botany questions on the life cycle of a conifer...?

Question

1.) In terms of chromosome number, how do an egg cell and a sperm cell differ from a seed?

2.) What is the adaptive advantage of a plant that produces seeds with "wings"?

I can't find it on wikipedia, my textbook or on google...maybe I'm searching for the wrong thing, but I really don't get it.

Answer 1

1) Both egg and sperm cell are haploid, this means they only have one set of chromosomes; when the egg and the sperm get together (fecundation) they make an embryo. Now a seed is an embryo which is dormant (this means waiting for the good conditions to grow), which is a diploid, this means the seed has two sets of chormosomes, one from the egg and another from the sperm cell.

2) The advantage is that it the wings can disperse a seed further, it has a more aerodynamic form, so wind can disperse it more effectively.
:o)

Answer 2

Plants have a reproductive stage animals do not. Their sperm/pollen can survive for a period with stored water & nutrients away from the the parent plant. The pollen and egg still have to combine to make another entire individual just as in animals so their chromosome count is haploid (n). This combination of gametes makes a diploid (2n) seed encased embryo in plants and a egg shell encased embryo or uterine encased embryo in animals. Haploid number is the basic chromosome count (n) for gametes. Diploid is the paired chromosome count (2n) for organisms once the gametes merge.
The reason plants want their offspring separate, like a seed, is so it can move carried by wind, water, or animals to a new location. Animals can move so they carry their offspring to good birthing locations.

Seeds that are passively carried by wind have to be very small so can carry very little water and food stores. With small reserves they can't live long. They also will not travel very far usually. If they have lift mechanisms like wings they can carry more, living longer and go farther.

Answer 3

ok...
sperm and egg cells are 'haploid", meaning they only have 1 set of chromosomes. a seed is 'diploid', meaning that it has 2 sets of chormosomes (ie 1 set from each sex cell - sperm and egg)

a seed with wings will find their advantage when being dispersed by wind. Wings help the seed 'catch' the air and so can travel further than seeds without wings

Answer 4

2) To aid in dispersal. Wings allow wind to carry seeds greater distances.