26 is sexual reproduction. There are two types of reproduction, sexual and asexual. The biggest difference between them is how many organisms you need. For asexual reproduction only one organism is needed. Usually this is bacteria and prokaryotes. They just divide themselves into copies of themselves. For sexual reproduction two organisms are needed to create offspring. The offspring gets its traits from its parents.
27 is fertilization, when the sperm fertilizes the egg and creates a zygote (or a fertilized egg).
28. Since each parent gives its offspring traits, the offspring will have a mixture of alleles from both parents. Some will be from mom, some will be from dad. This all depends on the alleles and whether the traits are dominant or heterozygous and which ones the offspring gets.
