I don't understand diploid and haploid question, please help?

Think of the two terms like this - a diploid cell (from the Greek word diplous meaning double) has double the amount of chromosomes as the haploid cell, while the haploid (from the Greek word haplous meaning single) has half the amount of chromosomes as the diploid. It's a little bit of circular reasoning, but it works when you have one or the other.

In humans, sex cells are always going to be haploid and somatic cells are always going to be diploid. So...

1) The sperm cell has 20 chromosomes. It's haploid since it's a sex cell, so the "regular" cells would have twice as many copies of chromosomes and would therefore have 40.

For the second question, you need to know that meiosis occurring in a single diploid cell will produce four haploid daughter cells. That's just how meiosis works. So...

2) The diploid cell has 18 chromosomes, therefore the haploid cells will have half the amount of chromosome copies and each have 9. And as we said before, there will be 4 of those daughter (sperm) cells.

*edit*

To further clarify where the 4 daughter cells come from, look at a diagram of meiosis. The diploid cell will divide into two cells in meiosis I, and then divide again in meiosis II. In short, one cell splits, then splits again to give rise to four cells.

Okay...

All somatic cells in animals are diploid.

You are a combo of your mum and dad; they both gave you a set of genes.

Sex cells are what you use to pass on genes. They have half of the normal chromosome count, since they will combine with another sex cell to form a person.

Haploid egg+ haploid sperm= diploid zygote

Haploid--> half Diploid-->full

as for the other question, 4 sperm are produced when males undergo meiosis. Women would produce four as well, but the other three turn into polar bodies.

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