Answer:
oxygen enters blood cells by 'diffusion'
The pituitary gland, otherwise known as the hypophysis cerebri, is a small gland that is about the size of a pea. It’s
often called the “master gland” because it produces the hormones that stimulate the function of other endocrine
glands. It’s located at the base of the brain on the hypothalamus and is divided into two lobes—<u>anterior lobe and
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<u>posterior lobe.
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The four important characteristics of respiratory surface are:
1. Thin walls
2. Moisture
3. Large surface area
4. Blood supply
Respiratory system or respiratory tract is divided into upper and lower tract. Upper respiratory tract includes nose and its cavities, sinuses, pharynx and the part of the larynx. Lower respiratory tract consists of the trachea, bronchi, bronchioles and the alveoli.
Alveoli are the ends of the respiratory tract the smallest units in it. Alveoli are small folded air sacs that are branching off from alveolar ducts and providing an extremely large surface area for the gas exchange. Gas exchange occurs thanks to small blood vessels – capillaries that surround alveoli and it occurs via the process of diffusion.
So, respiratory surface is thin membrane also known as the blood–air barrier that consists of the alveolar epithelial cells, their basement membranes and the endothelial cells of the alveolar capillaries.
Partial or complete loss of hearing can be caused by damage to the; I, II, and III, that is, the axons of the neurons associated with each hair cell that carry information to the brain, hair cells in the cochlea and also the tympanic membrane. Hearing impairment, deafness or hearing loss is the inability to hear things, either totally or partially. This may be caused by injury or diseases that damages the parts responsible for hearing process.
Answer : A metal in group 16 of the periodic table can become a chemically stable ion by gaining 2 electrons.
Explanation :
The group 16 element are oxygen, sulfur, selenium, tellurium and polonium.
The general electronic configuration of group 16 elements is, 
As we now that there are total 6 electrons in p sub-shell. So, a metal in group 16 can become a chemically stable ion by gaining 2 electrons.
Hence, a metal in group 16 of the periodic table can become a chemically stable ion by gaining 2 electrons.
