This question is very good
The fertilized cell that results is referred to as a zygote. A zygote is diploid cell, which means that it has twice the number of chromosomes as a gamete
I don’t understand the question but if I can make a correct inference, they have thorns to protect themselves from predators.
The pituitary gland secretes a hormone called antidiuretic hormone (ADH) which reabsorbs water in the kidney from the urine
A plant is is a Eukaryotic (if that’s what you meant) and here are some note I took last year, hope they help :)
