Answer:
The correct answer would be d. thymus.
The thymus is a specialized lymphoid organ of an immune system.
It serves as the site for training and maturation of T-lymphocytes or T cells.
It is composed two identical lobes each containing outer region termed as cortex and inner region termed as medulla.
T-cells are first trained and selected in the cortex region via positive selection. In this, T cells which are able to bind to foreign antigens are selected and rest are degraded.
The selected T cells then move in the medulla region where they are selected by negative selection. In this, the T cells which binds to self-antigens are degraded and rest survive to become functional T cells.
Answer:
D. O
Explanation:
Blood type O- is often referred to as the universal donor. If someone has lost an excessive amount of blood and their blood type is unknown. It is safe to use a type of blood that anyone can accept without being rejected by the human body.
Answer:
lose more heat to the environment in cold environments
Explanation:
This is because as an animal have large surface area, it is exposed largely and prone to loss of heat. The larger the size of an animal, the larger the surface area and volume. It's surface area expose the tendency for the animal to sweat alot , through sweating heat is loss to the environment. In cold environment, the animal try to maintain internal homeostasis and through this heat is generated and loss to the environment.
Answer:
pollution
Explanation:
Pollution is the introduction of contaminants into the natural environment that cause adverse change.
