Answer: The correct answer is- A. Chromosome numbers vary widely.
Chromosome can be described as thread like structure that is composed of DNA ( deoxyribonucleic acid) and possesses genes ( segment of DNA coding for a particular protein) on it.
Eukaryotic cells ( such as plant cell, animal cell) have variable number of chromosomes.
For instance, human beings have 23 pairs of chromosomes whereas it is different in plants depending on the species.
Thus, A) is the right answer.
The serous membrane that protects the heart, lungs and abdominal cavity is; ( Visceral pericardium ) Sorry if I’m wrong‼️
Answer:
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Answer:
A) stratum basale.
Explanation:
The epidermal layer consists of five layers. This is not having any blood vessels and known as avascular. The four-layer starting from stratum basale to stratum corneum is referred to as thin skin. But the skins of foot and palm has another layer called stratum lucidum. This layer forms the five layers of the epidermis.
The stratum basale is the deep layer of the epidermis. Below this layer dermis is present. This layer consists of basal cells which are precursors of keratinocyte cells. The stratum basale is a single layer cell and it undergoes continual mitosis. So that this cell produces new cells and these new cells replace the other older cells above it.
As the basal cells are precursors of keratinocytes, they produce all keratinocytes of the epidermis.
Two other types of cells are produced from this layer - Merkel cell, and melanocyte. Merkel cells act as touch receptors and melanocytes produce melanin pigments.
The
Thymocyte progenitors enter the subcapsular region of the thymus as
double-negative cd3- t cells where the double negative refers to lack of
cluster determinants CD4 and CD8. Double-negative cd3- t cells exist as small population
that is 1%-5% of lymphocytes in the lymphoid organs and peripheral blood of
humans and normal rodents.
