D. homologous chromosomes pair up
The pluripotent, undifferentiated cells in the bone marrow that give rise to the formed elements are called stem cells.
Pluripotent stem cells have the ability to undergo self-renewal and to give rise to all cells of the tissues of the body. However, this definition has been recently complicated by the existence of distinct cellular states that display these features.
There are two types of pluripotent stem cells :
- Embryonic stem cells (ESCs)
- Induced pluripotent stem cells
Embryonic stem cells are derived from the inner cell mass (ICM) of pre-implantation embryos and can be indefinitely maintained and expanded in the pluripotent state in vitro. Pluripotent stem cells can also be obtained by inducing dedifferentiation of adult somatic cells through a recently developed in vitro technology, known as cell reprogramming.
Similarly to Embryonic stem cells , Induced pluripotent stem cells can be expanded indefinitely and they are capable to differentiate in all the derivatives of the three germ layers.
Another intriguing features of being pluripotent is its reliance on gene expression heterogeneity.
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They reproduce by pollination.
Answer:
The correct option is D: Being prepared for harsh weather conditions
Explanation:
Plants are sensitive to the changes in the environment and any drastic changes in their surroundings can potentially cause the plant to go into stress, or possibly even die. Too high or low a temperature and the plant will not be able to cope. Similarly, drastic changes in water levels will really affect its health and growth.
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Ans.
Tuberculosis (TB) is a bacterial infection that affects mainly respiratory tract and can be transmitted from one to another person through contaminated air. The causative agent of tuberculosis, <em>Mycobacterium tuberculosis</em> has developed resistance against many antibiotics, such as rifampin and isoniazid, which is known as tuberculosis drug resistance.
If a person infected with TB shows drug resistance against some TB drugs, 'doctors should give other TB drugs to that person, even if these drugs show less effect than common drugs'. This is because these drugs can prevent or kill the bacterium more effectively than the common drugs for which, bacterium is resistance.
