Biology Test - 58

In eukaryotes the complete oxidation of a molecule of glucose results in the net gain of \(38\) molecules of ATP.

Complete oxidation of glucose occurs through three steps :

• Glycolysis
• Krebs cycle
• Terminal oxidation

During glycolysis glucose changes to pyruvic acid gaining total energy as \(2\) ATP molecules and \(2\) molecules of \(NADH _{2}\) then later on in Krebs cycle 30 ATP molecules and \(2 F A D H_{2}\) are produced. One \(NADH H _{2}\) produces \(3\) ATP molecules while one \(F ADH _{2}\) produces two ATP molecules. Therefore in complete oxidation of one molecule of glucose, a total of \(38\) ATP's are gained.

It took millions of years for life to appear on Earth after the planet had formed because the planet had cooled down enough to sustain life.

The first evidence of life on Earth from microscopic fossils remains of microorganisms corresponds to the time when the planet had reached a cool enough temperature for any life to survive.

Loss of one chromosome from one set is calledMonosomy.

Aneuploidy is caused by nondisjunction, which occurs when pairs of homologous chromosomes or sister chromatids fail to separate during meiosis. The loss of a single chromosome from a diploid genome is called monosomy (2n-1), while the gain of one chromosome is called trisomy (2n+1).

The proximal convoluted tubule is lined by simple cuboidal brush border epithelium which increases the surface area for reabsorption. Nearly all of the essential nutrients and 70-80 percent of electrolytes and water are reabsorbed by this segment. Glucose is completely reabsorbed from PCT under normal conditions. But in conditions like diabetes mellitus glucose is not completely reabsorbed in the renal tubule because of which glucose is found in urine. The presence of glucose in urine is called as glycosuria.

DNA precipitation out of a mixture of biomolecules can be achieved by treatment with chilled ethanol.

At a nuclear level, the decrease in the power following up on a charge results from water atoms framing a hydration shell around it. This reality makes water an excellent dissolvable for charged mixes like salts. Electric power which regularly holds salt gems together via ionic securities is debilitated within the sight of water permitting particles to isolate from the gem and spread through arrangement.

A similar system works on account of contrarily charged phosphate bunches on a DNA spine: despite the fact that positive particles are available in arrangement, the generally feeble net electrostatic power keeps them from framing stable ionic bonds with phosphates and accelerating out of arrangement.

Chilled ethanol is substantially less polar than water, with a dielectric constant of 24.3 (at 25 °C). This implies that adding ethanol to arrangement upsets the screening of charges by water. In the event that enough ethanol is added, the electrical fascination between phosphate gatherings and any sure particles present in arrangement gets sufficiently able to shape stable ionic bonds and DNA precipitation. This generally happens when ethanol makes over 64% out of the arrangement. As the instrument proposes, the arrangement needs to contain positive particles for precipitation to happen; normally Na⁺, NH4⁺ or Li⁺ assumes this job.

Least genetic diversity is a characteristic feature of cropland ecosystem.

A crop land ecosystem will have a major crop cultivated in a given area. It shows that the diversity in that particular area will be least. Whereas it is the opposite when forest ecosystem is considered.

The cropland Ecosystem:

This is manmade ecosystem. Man has been doing his best in modifying the croplands to get maximum benefit out of them. A cropland ecosystem may be illustrated by crops like wheat, maize, rice, sugarcane etc. It has following components.

1. Producers: A crop along with the weeds growing in the field are the producers of a cropland ecosystem. In the cropland ecosystem of maize, weeds like Cynodon dactylon, Euphorbia hirta, Alysicarpus, Launea nudicairlis are very common.

2. Consumers: Herbivores are the primary consumers of the cropland ecosystem. These include rats, rabbits, birds, man and insects. The second order and the third order consumers are represented by frogs, snakes, birds such as hawk etc.

3. Decomposers and transformers: Bacteria and fungi like Bacillus, Aspergillus, Clostridium, Agaricus, Mucor, Aspergillus and Fusarium are common decomposers and transformers of cropland ecosystem of maize.

There are four such a reaction in which electron is transferred from substrate to electron accepting enzyme. In three of these, \(NAD^+\) is reduced to \(NADH\) and in one \(FAD\) reduces to \(FADH_{2}\).

Perfusion is not a renal function. It is a process of passage of fluid through circulatory system to an organ or a tissue.

Reabsorption is an important function of kidney where water and solutes are removed from the tubule and returns back to the blood.

Filtration is also a renal function as it passes the solute and water from the plasma to the renal tubule.

Secretion is an opposite function of reabsorption where the waste is removed from blood capillaries and excreted out of the body.

The exchange of segments of two non-homologous chromosomes is termed translocation.

In genetics, a chromosome translocation is a chromosome abnormality caused by the rearrangement of parts between nonhomologous chromosomes. A gene fusion may be created when the translocation joins two otherwise separated genes, it is detected on cytogenetics or a karyotype of affected cells.

DNA is deoxyribonucleic acid. All the 23 pair chromosomes carry DNA. These are double-stranded coiled helices. These have two polypeptide strands. The model of DNA was given by Watson and Crick. X-Crystallography was used to identify the structure. The human genome is a set of nucleic acids sequences in the case of humans which is encoded as DNA with all 23 pairs of chromosomes in cell nuclei. DNA is deoxyribonucleic acid. It is composed of two polynucleotide chains. They coil around each other forming a helix. It carries information about the genetic development, growth, and functioning of an individual. These also carry the physical trait genes from the parents. A DNA molecule has a sugar, phosphate, and purine/pyrimidine group. It is usually present in the nucleus of the cell as it is the center of genetic information. Other than the nucleus, the mitochondria and chloroplast have their DNA. The lysosome is the membrane organelles, formed from the Golgi apparatus. Their major function is to remove the waste from the cell. The autolysis is the process of destruction of a cell which is carried out by the lysosome. Thus the enzymes like DNase, Rnase, protease, etc. are present in them to digest the macromolecules and nucleic acids. The vacuole is a bubbles-like structure, found in animal and plant cells, which store the food or nutrients. They can also have waste products to protect the cell from contamination. There are a larger number of vacuoles in a cell. Their main function is to store nutrients and food.

Option (A): Mitochondria and lysosomes: Lysosomes are deprived of DNA but the mitochondria have their DNA.

Option (B): Chloroplast and vacuoles: Chloroplast have the DNA but the vacuole does not have.

Option (C): Lysosomes and vacuoles: They both do not have DNA in them.

Option (D): Nuclear envelope and Mitochondria: They have their genetic makeup of DNA.