Biology Test-5

Maintenance and in-vitro growth of plant cells, tissues, and organs on a suitable culture medium are known as tissue culture. The growth regulators commonly used in plant tissue culture are 2,4-D auxins and cytokinins, such as benzyl amino purine (BAP). These growth regulators are required for cell division and organ regeneration from the tissue cultures.

ZIFT is Zygote Intra-fallopian Transfer. In this technique, ova from female and sperms from the male are collected and are induced to form a zygote in the laboratory under simulated conditions. The zygote or early embryo up to 8 blastomeres is transferred into the fallopian tube, therefore it is known as Zygote intra-fallopian transfer and an embryo with more than 8 blastomeres is transferred into the uterus.

Latimeria chalumnae also known as The Coelacanth is a living fossil. It belongs to the group crossopterygii, from which amphibians are thought to be evolved. It is the oldest living fish and has survived till today without undergoing any change. It was first caught in the east coast of South Africa.

Wings of birds and bat is an example of Analogous organs.

Analogy is the study of organisms with structures that are not anatomically similar but perform similar functions. There is no common ancestor between the two organisms. They are actually a product of convergent evolution. Example of analogy includes the structure of wings of a butterfly and of birds that are not looking anatomically similar but they perform similar functions.

The stage in cell division that consists of the G1 phase, S phase, G2 phase is the Interphase.

Interphase is the period between the end of one cell division to the beginning of the next cell division. The interphase takes almost 95% of the total time of the cell cycle. During interphase the cell prepares itself for the next division, it grows in size. So the cell is the most active metabolically in Interphase.

Interphase is divided into 3 phases:

1. G1 phase/Post mitotic/Pre-DNA synthetic phase/Ist gap phase
2. S-phase/Synthetic phase
3. G2-phase/Pre mitotic/Post synthetic phase/IInd gap phase.

Cell growth: It is the period of synthesis and duplication of various components of the cell.

Cell Division is the process by which a mature cell divides and forms 2 nearly equal daughter cells which resemble the parental cell in a number of characteristics. 2 processes take place during cell reproduction. It is the process when a mature cell divides into two cells. The Cell cycle completes in 2 steps: 

1. Interphase
2. M-phase/Dividing phase

A single chromosome contains only one DNA (deoxyribonucleic acid) molecule and so many genes. Humans have 23 pairs of chromosomes.

• 22 pairs of autosomes chromosomes and one pair of sex chromosomes, X and Y.

The information in DNA (double helix structure) is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).

• DNA has two base pairs, A-T and G-C, attached to a sugar-phosphate backbone.

In the cell nucleus, the DNA molecule is packaged into thread-like structures called chromosomes.

• A chromosome (microscopic structure) is made up of DNA tightly coiled many times around proteins called histones that support its structure.
• A chromosome has two arms - p arm (short arm) and q arm (long arm), joined in the location of the centromere.

Among the options, only Cytokinin is a plant hormone. Cytokinin helps in the rapid cell division in plants. Cytokinin is largely present in coconut water.

The two types of cytokinins are:

1. Adenine-type cytokinins.
2. Phenylurea-type cytokinins.

Cytokinins are involved in plant processes like cell division and shoot and root morphogenesis. Farmers use cytokinin to increase crops.

• Melatonin is the hormone secreted by the Pineal gland. Melatonin is also called the hormone of darkness. Melatonin regulates the circadian rhythm of the human body. The deficiency of melatonin caused sleeplessness.
• Gastrin is a peptide hormone released by the G cells in the pyloric antrum of the stomach, duodenum, and pancreas.
• Cholecystokinin is a peptide hormone secreted by the enteroendocrine cells in the duodenum.

Glycolysis occurs in Cytoplasm part of the cell.

Glycolysis:

• The term glycolysis has originated from the Greek words, glycos for sugar, and lysis for splitting.
• The scheme of glycolysis was given by Gustav Embden, Otto Meyerhof, and J. Parnas, and is often referred to as the EMP pathway.
• In anaerobic organisms, it is the only process in respiration.
• Glycolysis occurs in the cytoplasm of the cell and is present in all living organisms.
• In this process, glucose undergoes partial oxidation to form two molecules of pyruvic acid.
• In plants, this glucose is derived from sucrose, which is the end product of photosynthesis, or from storage carbohydrates.
• Sucrose is converted into glucose and fructose by the enzyme, invertase, and these two monosaccharides readily enter the glycolytic pathway.
• Glucose and fructose are phosphorylated to give rise to glucose-6- phosphate by the activity of the enzyme hexokinase.
• This phosphorylated form of glucose then isomerizes to produce fructose-6- phosphate.
• Subsequent steps of the metabolism of glucose and fructose are the same.
• In glycolysis, a chain of ten reactions, under the control of different enzymes, takes place to produce pyruvate from glucose.

Alveoli is the tiny part inside the lungs where the exchange of oxygen and carbon dioxide actually takes place. Each person has hundreds of millions of alveoli in their lungs. The Trachea (windpipe) is the main passage leading from your nose to the lungs. The trachea divides into two main Bronchi (tubes), one for each lung. The bronchi, in turn, subdivide further into bronchioles. The smallest section of the bronchi is called Bronchioles, at the end of which are the alveoli (plural of alveolus). Every few seconds, with each inhalation, air fills a large portion of the millions of alveoli. In a process called diffusion, oxygen moves from the alveoli to the blood through the capillaries (tiny blood vessels) lining the alveolar walls. Once in the bloodstream, oxygen gets picked up by the hemoglobin in red blood cells. This oxygen-rich blood then flows back to the heart, which pumps it through the arteries to oxygen-hungry tissues throughout the body. In the tiny capillaries of the body tissues, oxygen is freed from the hemoglobin and moves into the cells. Carbon dioxide, made by the cells as they do their work, moves out of the cells into the capillaries, where most of it dissolves in the plasma of the blood. Blood rich in carbon dioxide then returns to the heart via the veins. From the heart, this blood is pumped to the lungs, where carbon dioxide passes into the alveoli to be exhaled.

Medulla Oblongata is the part of the brain that controls the heart.

Human brain is the central organ of the human nervous system. The brain can be divided into three basic units: the forebrain, the midbrain, and the hindbrain.

Fore-brain:

The forebrain structures include the cerebrum, thalamus, hypothalamus, pituitary gland. Cerebral hemispheres make up the uppermost portion of the brain and are involved in the sensory mechanisms, control of voluntary movements, such as speech. The thalamus is the main relay centre between the medulla oblongata and the cerebrum. Hypothalamus is an important control centre for sex drive, pleasure, pain, hunger, thirst, blood pressure, body temperature, and other visceral functions. Hypothalamus produces hormones that control the secretions of the anterior pituitary gland, and it also produces oxytocin.

Mid-brain:

The midbrain lies between the thalamus and pons. Midbrain serves important functions in motor movement, particularly movements of the eye, and in auditory and visual processing.

Hind-brain:

There are three main parts of the hindbrain - pons, cerebellum, and medulla oblongata.

• Pons regulate respiration.
• The cerebellum helps with the coordination and movement related to motor skills, especially involving the hands and feet.
• Medulla Oblongata plays an essential role in passing messages between your spinal cord and brain.
• It's also essential for regulating your cardiovascular(Heart) and respiratory systems.

Aspergillusare used for the commercial production of citric acid.

Citric acid is the most important organic acid produced in tonnage and is extensively used in the food and pharmaceutical industries. It is produced mainly by submerged fermentation using Aspergillus niger or Candida sp. from different sources of carbohydrates, such as molasses and starch-based media.

Usnic acid is an antibiotic obtained fromLichens.

An antibiotic is a substance that inhibits the growth of the bacteria or directly kills the bacteria. Usually, many fungi species are identified which have antibiotic properties. For example, penicillin is obtained from a fungus and it is a wide range of antibiotics that kills many bacterial species. Except for fungus, many species of lichens are also reported to synthesize antibiotic compounds like usnic acid. Usnic acid is a yellow crystalline acidic compound having the molecular formula C₁₈H₁₆O₇.

It is a naturally occurring antibiotic that is found in many lichen species. The lichens are the symbiotic associations of fungi and algae. These are found growing over barks of trees, stone surfaces, rotting materials, etc. they stay attached to the substratum. Both fungi and algae benefited from this association. They secrete many compounds including antibiotics to sustain their safe development. The usnic acid was found to be synthesized by various lichen species namely Usnea, Cladonia, Alectoria, etc. It is believed that usnic acid in lichens is used to protect them from the harmful effects of sunlight. It is a secondary metabolite of lichens. This means that it is a waste-type secretory product of lichens. Also, the bitter taste of usnic acid protects the lichens from grazing animals.

Note: Many fungal and lichen species secrete antibiotics naturally. The use of antibiotics in the pharmaceutical industry has saved millions of lives from deadly bacterial infections. But due to the un-sustained use of antibiotic medicines, the bacteria have become resistant to them. This is called antibiotic resistance. This causes a greater threat to future health emergencies. Thus, alternatives need to be found.