Answer:
The Thymus is a unique gland which protects the body against autoimmunity when the immune system act against itself.Hence the Thymus plays a significant role the dual systems i.e.,the lymphatic system (body’s defensive mechanism) and the endocrine system
Explanation:
The Thymus is special gland located anteriorly to the chest directly behind the sternum and in between the lungs. Active until puberty and gradually shrinks to become fat after puberty.
Function: Prior to birth and during childhood thymus engage in producing and maturation of T-lymphocytes or T-cells a particular type of white blood cells which defence the body against infectious disease germs.Though the organ does not function throughout the life span but it plays a significant role protecting the body against autoimmunity refers to an immune system works against itself .Therefore the thymus plays a key role in lymphatic system and an endocrine system.
Secretion:Thymus secretes Thymosin a hormone it instigates the development of T-Cells ( disease resisting cells) Thymosin stimulates the development of T-Cells until a human attains its puberty.
At the age of 75 thymus becomes a fatty tissue.
Answer:
"As a molecule moves through the plasma membrane it passes through <em>a hydrophilic layer of phospholipid heads then a hydrophobic layer of phospholipid tails and then another hydrophilic layer of phospholipid heads".</em>
Explanation:
Biological membranes are formed by two lipidic layers, proteins, and glucans.
Lipids characterize for being amphipathic molecules, which means that they have both a hydrophilic portion and a hydrophobic portion at the same time. These molecules have a lipidic head that corresponds to a negatively charged phosphate group, which is the polar and hydrophilic portion. They also have two lipidic tails that correspond to the hydrocarbon chains -the apolar and hydrophobic portion- of the fatty acids that esterify glycerol.
Membrane lipids are arranged with their hydrophilic polar heads facing the exterior and the interior of the cells, while their hydrophobic tails are against each other, constituting the internal part of the membrane.
Through this lipidic bilayer, some molecules can move from one side of the cell to the other, which happens because of concentration differences. When this occurs, molecules must pass through the hydrophilic layer of phospholipid heads then through the hydrophobic layer of phospholipid tails and then again through another hydrophilic layer of phospholipid heads.
Answer:
C. True.
Explanation:
It should be understood that the the percentage of nitrogen is the highest in the atmosphere. This is because, it make up of more than 60% of the atmosphere. And it should be noted that the atmospheric nitrogen is inform that can not be used by the plant.
Therefore, there is a need for a certain group of bacteria which live in the root noodles of the plants to convert the unused form of the atmospheric nitrogen to a form that can be used by the plants.
These are called Temperate zones because of the variety in temperatures throughout the year and the more distinct seasonal changes
