Tag: tissues of animals

The external surfaces and internal linings of the animal body are made up of various kinds of epithelial tissues. Epithelial tissues have various functions all across our bodies like secretion, absorption, protection, sensing and, to some extent, thermoregulation. So, the correct answer is 'Epithelial'.

• Guard cells are cells surrounding each stoma. They help to regulate the rate of transpiration by opening and closing the stomata. 
• Lenticels are one of many raised pores in the stem of a woody plant that allows gas exchange between the atmosphere and the internal tissues. Bulliform cells are large, bubble-shaped epidermal cells that occur in groups on the upper surface of the leaves of many grasses. Loss of turgor pressure in these cells causes leaves to "roll-up" during water stress. 
• Subsidiary cell is a plant epidermal cell that is located next to a guard cell in the stoma of a leaf and differs in structure from other epidermal cells. Also called an accessory cell.

The epidermis is the outermost cellular layer which covers the whole plant structure, i.e., it covers roots, stem, leaves, flowers and fruit. It is composed of a single layer of living cells, although there are exceptions. The function of epidermal cells are as follows-

Promeristem are groups of meristematic cells found in germinating embryos or young seedlings. They give rise to primary meristems which initiate the organ formation process. Promeristems are also referred as primordial meristems or embryonic meristems because of their origin.
Thus, the correct answer is option A.

Dermatogen is also known as protoderm which further divides to form the three dermal layer which is epidermis, endodermis and hypodermis. These form the protective layer of the plant. Epidermis is the outer layer which mainly bears small opening known as stomata.
Therefore, the correct answer is option B.

• Cardiac muscle is a type of involuntary striated muscle found only in the walls of the heart. 
• This is a specialized muscle that, while similar in some fundamental ways to smooth muscle and skeletal muscle, has a unique structure and with an ability not possessed by muscle tissue elsewhere in the body. 
• Cardiac muscle, like other muscles, can contract, but it can also carry an action potential (i.e., conduct electricity), like the neurons that constitute nerves.
•  Furthermore, some of the cells have the ability to generate an action potential, known as cardiac muscle automaticity. Cardiac muscle is adapted to be highly resistant to fatigue:
•  it has a large number of mitochondria, enabling continuous aerobic respiration, numerous myoglobins (oxygen-storing pigment), and a good blood supply, which provides nutrients and oxygen. 

Howard and Pelc divided cell cycle in four stage. The cell cycle is an ordered set of events, culminating in cell growth and division into two daughter cells. Non-dividing cells not considered to be in the cell cycle. The stages  are G$ _1$-S-G$ _2$-M. The G$ _1$ stage stands for "GAP 1". The S stage stands for "Synthesis". This is the stage when DNA replication occurs. The G$ _2$ stage stands for "GAP 2". The M stage stands for "mitosis", and is when and cytoplasmic division occur.

A person with blood group O is considered as universal donor as it does not contain any antigens which can trigger the production of antibodies in a person with any of the other three blood groups i.e. A, B or AB. Thus, option D is correct.

There are six possible genotypes for the ABO blood groups in human.
The chart here shows the different genotypes, that make up the blood groups.
Therefore, the correct answer is option C.