5 chromosomes. Meiosis results in 4 haploid cells, meaning they have "n" pairs of chromosomes. The diploid cell that the 10 chromosomes originated in has "2n" pairs. This leaves us with a simple equation to solve the problem, 2n=10, so n must equal 5 chromosomes.
About 11 to 15 days after conception the zygote attach to the uterine wall
A group of similar (accoding to function) types of cells, when comes together to perform a specific function, then it forms a tissues.
When a group of similarly working tissues come together then they form an organ.
And this relation could be written as
cell > tissue > organ
So, organ is a collection of tissues and tissues are collection of cells.
I am not sure about the second one, but I know the first one.
The answer is D.
"An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. Irregular galaxies do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure."