Answer:
The correct answer is: Immunosenescence.
Explanation:
- Immunosenescence can be defined as a biological age-related phenomenon due to which the cells of the immune system are unable to function efficiently with increase in age.
- As a result of this the aged individuals becomes susceptible to various infections and diseases.
- This happens because of the following reasons:
- The immune cells are formed from the progenitor cells called the Hematopoetic Stem Cells (HSCs) which are abundantly found in the bone marrow. These cells have the capacity of self-renewal and also differentiation into various types of immune cells. Due to aging, these cells accumulate large number of Reactive Oxygen Species (ROS) that that causes oxidative damage to the DNA. Also, with age the telomere (the repititive DNA sequence located at the chromosome terminal that protects the end of the chromosome from undergoing recombination or fusion with other chromosomes) length shortens resulting in the generation of damage in DNA. All these reduces the self renewal and differentiation capacity of these cells.
- Other cells of the immune system like, the white blood cells, anti-body producing B-cells, cytotoxicity inducing T-cells, natural killer cells also accumulate similar DNA degrading components. This reduces their life time and also the efficiency of their activity.
The answer is C genetic variation
Answer: There are two ways to determine the age of a dinosaur fossil. One is called relative geologic time, which involves deciding whether one dinosaur fossil is older or younger than another. Geologists then measure the proportion of parent and daughter atoms present in the ash crystals to determine the crystal's age.
Explanation:
Even being a visual learner the trick is to take notes, even if you never look at the notes ever again its good to write them down, you are more likely to remember something you have written down rather than to just look at it. Science is something that could be easy, you just have to take it at your own pace, don't try to learn science by giving it a quick read or glance at it.
The shoulder is Lateral to the neck.
<h3>Is the shoulder lateral or medial?</h3>
Away from the median plane of the body (ex: the shoulder is lateral to the head or the ear is sideways to the brain). Medial: toward the median plane of the body (ex: the head is medial to the shoulder or the nose is medial to the cheek).
Thus, option "A" is correct.
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