Define the following:
i) Homeostasis
ii) Pseudopodia
iii) Hermaphroditism
iv) Taxis
v) Binary fission
Solution
(1)
Homeostasis is the process by which an organism keeps its internal environment constant in response to fluctuations in its external environment. This mechanism, which comprises a network of feedback loops that continuously monitor and change the body’s internal environment, is crucial for the health of the body’s cells, tissues, and organs.
Maintaining a constant internal body temperature is one example of homeostasis. The sweat glands in your skin secrete perspiration to assist cool you down when your body detects a rise in temperature. Muscles contract to create heat and blood vessels constrict to preserve heat when the body is exposed to cold.
The maintenance of constant blood sugar levels is another example of homeostasis. The pancreas secretes insulin in response to a rise in blood glucose levels, allowing cells to take in and store the glucose for later use as fuel. To counteract this effect, the pancreas secretes glucagon when blood glucose levels fall, prompting the liver to release glucose into the blood. An adequate blood glucose level is crucial for the health of the body’s cells and organs, and this is achieved by a combination of techniques.
(2)
Pseudopodia are short-lived membrane extensions that let cells move and engage in phagocytosis. They may swiftly expand and retract and are present in specific types of cells including amoebas and white blood cells.
The cytoskeleton, the network of protein fibres that gives cells their shape and structure, is reorganised to generate pseudopodia. In particular, the direction of motion is indicated by a bulge in the cell membrane caused by the fast polymerization and depolymerization of actin filaments within the cell.
Amoebas use pseudopodia to propel themselves through the water and soil in search of food. As it moves, the amoeba grips the surface with its pseudopodia and pulls itself along. Similarly, white blood cells may grow pseudopodia around a foreign particle, enveloping and bringing it inside the cell to be destroyed.
(3)
When a person is born with both male and female reproductive organs, this is called hermaphroditism. Because of this, hermaphrodites can reproduce sexually on both sexes and show signs of both sexism and transgenderism.
Hermaphroditism can occur in two distinct ways: simultaneously and sequentially. Those with both male and female reproductive organs at the same time are said to exhibit simultaneous hermaphroditism. All members of some fish species, like the clownfish, are born male but can undergo a sex change to become female if necessary.
The term “sequential hermaphroditism” is used to describe people who undergo sex transitions at different points in their lives. This can occur from male to female or female to male in both plants and animals. Certain kinds of wrasses, for instance, have individuals who are born female but can transition to male as they get older.
(4)
Taxis is the movement towards or away from a stimulus that occurs as a result of an organism’s behavioural reaction to the stimulus. It is common to use the term “taxis” to refer to the movement of single-celled creatures like bacteria or protozoa, but the term may also be used to refer to the movement of more sophisticated species.
Taxis come in a variety of forms, each catering to a certain set of circumstances or directional preferences. Taxis can be positive, in which case the organism moves towards a stimulus, or negative, in which case it moves away from it.
An organism’s movement towards or away from a chemical stimulus is called chemotaxis. Bacteria, for instance, may navigate towards a food supply by following a chemical gradient, and white blood cells can locate an infection site by responding to chemical signals emitted by the pathogen.
Another form of taxis, phototaxis includes an organism’s behaviour in response to light. Certain bugs, for instance, are drawn to lights and will fly towards them, while others will avoid them.
(5)
When one cell divides into two identical daughter cells, this process is called binary fission and is used for asexual reproduction. This is a frequent method of reproduction for unicellular organisms like bacteria and protozoa.
There are often numerous stages involved in a binary fission process. The first step in cell division is DNA replication, which ensures that each daughter cell retains an identical set of genetic instructions. The cell then elongates, and the two sets of DNA separate into distinct halves. At last, the membrane and wall of the cell contract in the centre, separating the cell into two daughter cells.
Since it facilitates quick reproduction and population development, binary fission is crucial for microbial communities. Pathogenic bacteria may rapidly proliferate and spread throughout the body of an infected host thanks to binary fission, which can also contribute to the development of infectious illnesses.