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Why is O2 necessary to complete the oxidation of glucose?
- When glucose is completely oxidized in aerobic cellular respiration, it produces thirty eighty molecules of Adenosine Triphosphate (ATP).
- Three processes take place in cellular respiration. These are glycolysis, Kreb's cycle, and electron transport chain reactions.
- Only glycolysis can occur in absence of oxygen, but the remaining two reactions will not take place. It produces alcohol if glycolysis occurs in absence of oxygen.
- By anaerobic glycolysis, only two molecules of ATP are produced. This results in less energy supplied to the body. Therefore, O2 is necessary for the entire oxidation of glucose.
Why are fibers considered as one of the important nutrients?
- Fibre are indigestible substance. They are thrown out along with other users and undigested matter.
- This aids in egestion. Some fibers also help in the digestion of other substances.
- Green leafy vegetables, fruit, serials are considered as important in the diet as they supply nutrients fibers. Thus, fibers are considered as one of the important nutrients.
Why is Cell division considered a very important property of cells and organisms?
- Cell division is very essential for all living organisms. The growth and development are possible only due to cell division.
- The emaciated body can be restored only through cell division which adds new cells. Offspring is produced only through the cell division that takes place in parents.
- In asexual reproduction, mitosis helps to give rise to a new generation.
- In sexual reproduction, meiosis helps to form haploid gametes. All such functions show that cell division is one of the important properties of cells and organisms.
Why do higher plants and animals also perform aerobic respiration?
- When there is a deficiency of oxygen in the surrounding, aerobic respiration is not possible.
- In such a case, to survive, higher plants switch over to anaerobic respiration. In some animal tissues, in case of oxygen deficiency, cells perform anaerobic respiration.
The Krebs cycle is also known as the citric acid cycle.
- Sir Hans Kreb proposed this cycle and hence it is called the Krebs cycle. These are series of cyclic chain reactions that begin with Acetyl coenzyme-A molecules that act with oxaloacetic acid molecules.
- The reactions are catalyzed with the help of specific enzymes. The first molecule formed in this reaction is called citric acid. Therefore, the Krebs cycle is also known as the citric acid cycle.
Explain the glycolysis in detail.
- Carbohydrates are converted to glucose after the process of digestion is completed. The oxidation of glucose for releasing energy is called glycolysis which takes place in the cytoplasm.
- Glycolysis can occur in the process presence of oxygen or without oxygen too. The first type of glycolysis takes place in aerobic respiration and the second type is anaerobic respiration. In aerobic respiration, stepwise oxidation of glucose molecules forms two molecules each of pyruvic acid, ATP, NADH2, and water.
- Later the pyruvic acid, formed in this process, is converted into molecules of Acetyl Coenzyme-A along with two molecules of NADH2 and two molecules of CO2.
- During anaerobic respiration along with glycolysis, there is fermentation too. This is incomplete oxidation of glucose and thus it results in the formation of lesser energy.
- The process of glycolysis was discovered by Gustav Embden, Otto Meyerhof, and Jacob Parnace. Therefore, in their honor, glycolysis is also called as Embden-Meyerhof-Parnas pathway (E-M-P pathway) for the discovery they had performed experiments on muscles.
How do all the life processes contribute to the growth and development of the body?
- Different systems work in coordination with each other in the body of the living organisms. In the human body, homeostasis is very advanced.
- The digestive system, respiratory system. nervous system, circulatory, excretory system, and all the external and internal organs in the body working independently, but in coordination with each other.
- The digested and absorbed nutrients of the food are transported to various cells with the help of the circulatory system due to the pumping of the heart. Simultaneously, the oxygen absorbed in the blood by the lungs is also transported to each cell by RBCs.
- Mitochondria in every cell bring about the oxidation of nutrients and produce the energy required for all of these functions.
- The control is exercised by the nervous system on all these actions. This keeps the organism alive and helps in the growth and development of the same.
Explain the Krebs cycle with reaction.
- Krebs cycle was proposed by Sir Hans Kreb. This cycle is named after him. It is also called the tricarboxylic acid cycle or citric acid cycle. The acetyl coenzyme-A molecules enter the mitochondria located in the cytoplasm.
- They participate in the chemical reactions taking place in the Krebs cycle.
- In cyclic chemical reactions, acetyl coenzyme-A is completely oxidized.
- It yields the molecule of CO2, H2O, NADH2, FADH2, and ATP upon complete oxidation.
"Explain the mitosis in detail."
There are two stages of mitosis. These are
- a) Karyokinesis or nuclear division and
- b) cytokinesis or cytoplasmic division.
Karyokinesis takes place in further four phases as prophase, metaphase, anaphase, and telophase.
a) Karyokinesis or nuclear division:
1) Prophase:
During prophase, condensation of chromosomes starts. The thin and thread-like chromosomes start thickening. They appear with the pair of sister chromatids. Duplicating The centrioles, it moves to the opposite poles of the animal cell. The nuclear membrane and nucleus are disappeared.
2) Metaphase:
Chromosomes complete the condensation process and appeared with their sister chromatids. The chromosomes appear in the equatorial plane of the cell. The spindle fibers are formed from the polar region where centrioles are present and they attach themselves to the centromere of each chromosome. The nuclear membrane now disappears completely.
3) Anaphase:
The centromeres of the chromosomes now divide and form two daughter chromosomes. The spindle fibers pull apart the chromosome from the equatorial region to the opposite poles. Moving chromosomes to the opposite poles appear like a bunch of bananas. Every set of chromosomes reach the pole by the end of the anaphase.
4) Telophase:
Telophase is the reversing event that occurs in the prophase. The thickened chromosomes become decondence. They again assume a thin and thread-like appearance. The nuclear membrane and nucleus appear again. The spindle fibers are completely lost. The cell has two nuclei now in one cytoplasm.
b) Cytokinesis:
A notch develops in the middle of the cell In animal cells. Deepening down this notch, later the cytoplasm divides into two. In the plant cells, forming cell plates, cytokinesis takes place.
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