Answer:
A
Explanation:
All living organisms pass on or transfer their genetic material to their offsprings. However, this transfer of genes occurs through the process of reproduction (sexual or asexual). Reproduction may (in case of sexual) or may not (in case of asexual) ensure genetic variation among species.
Eukaryotes that undergo sexual reproduction increase genetic variation among their species by undergoing Crossing-over (exchange of chromosomal segment between non-sister chromatids of homologous chromosomes) during meiosis or gamete formation. This process of transferring genetic material directly from parents to offsprings is called VERTICAL GENE TRANSFER, and only sexual-reproducing eukaryotes ensure genetic variation through this process.
On the other hand, prokaryotic organisms cannot undergo sexual reproduction, they undergo asexual reproduction instead and asexual reproduction does not guarantee genetic variation since identical daughter cells as the parents are produced from the process. However, to promote genetic variation among their species, they employ the processes of transformation, transduction and conjugation which are all forms of HORIZONTAL GENE TRANSFER because it involves transfer of genetic material from one cell (donor) to another (recipient) which do not have the parent-offspring relationship.
Red and White blood cells:
These are produced by the stem cells in the bone marrow. There are two types of stem cells for producing white blood cells - Myeloid stem cells (producing phagocytes such as neutrophils and monocytes - the undeveloped version of macrophages) and Lymphoid stem cells (responsible for production of lymphocytes such as B and T cells).
Because their bodies tell them that they need more oxygen and so breathe faster, and try and get the oxygen their body requires and depends on.
The answer is 300nm x 18nm
