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.
Lymphocytes generated during an initial infection that circulate in the body for years and quickly destroy that infection if it ever appears again are called the Memory t cells. These cells are a subset of infection that have previously encountered and responded to their respective antigen, thus they may be called the antigen experienced t cells.
The species likely living in an ecosystem on the other side of the mountain farthest from the coast is the cactus.
- Cacti are evergreen plants. Their stems might be meaty or succulent, cylindrical or flattened.
- The stems are green in colour and photosynthetic, usually fulfilling this job instead of leaves, which are scarce or nonexistent in most adult cacti.
Most cactus species are well-defended by spiky bristles and spines that repel most animals.
- Cacti are xerophytic plants, which means they are physiologically and morphologically suited to the high water shortages of dry ecosystems like deserts.
- Cacti's xerophytic adaptations include (1) succulent, water-retaining stems, (2) a thick, waxy cuticle, and few or no leaves to decrease water losses through transpiration.
Learn more about cactus here,
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Answer:
looks, feels, how hard it is, how soft, where it came from
Explanation:
