2. life processes in living organisms.-part-1
Q.1 fill in the blanks and explain the statement.
1. after complete oxidation of glucose molecules, 38 number of ATP molecules are formed.
2. at the end of glycolysis, pyruvate molecules are obtained.
3. genetic recombination occurs in pachytene phase of prophase of meiosis-1
4. all chromosomes are arranged parallel to equatorial plane of cell in metaphase of mitosis.
5. for formation of plasma membrane, phospholipid molecules are necessary.
6.our muscle cells perform anaerobic type of respiration during exercise.
Q.2 write definitions:
1.nutrition: the process of taking nutrients in the body and utilizing them by an organism is known as nutrition.
2.nutrients: the substances like carbohydrates, proteins, lipids, vitamins, minerals etc which are components of the food are called nutrients.
3. proteins: protein is a macromolecule which is formed by many amino acids which are joined by peptide bonds.
4.cellular respiration:oxidation of glucose and other food components which takes place inside the bcell in he presence or absence of oxygen,is known as cellular respiration.
5.Aerobic respiration:cellular respiration taking place in presence of oxygen is known as aerobic respiration.
6.Glycolysis;the process occurring in the cell where a molecule of glucose is oxidized in step by step process forming two molecules of each pyruvic acid,ATP,NADH2 and water,is called glycolysis.
Q.3 Distinguish between
1.glycolysis:
- the process of glycolysis occurs in the cytoplasm of the cell.
- in glycolysis, one molecule of glucose is oxidized step-by-step to produce two molecules each of pyruvic acid,ATP,NADH2 and water.
- glycolysis can take place in both aerobic and anaerobic respiration.
- the first step in cellular respiration is glycolysis where glucose is converted into pyruvate.
- two molecules of pyruvate are obtained in glycolysis.
- two molecules of ATP are used up in glycolysis.
- four molecules of ATP are produced in glycolysis.
- CO2 is not produced during glycolysis.
- TCA cycle takes place in mitochondria.
- in TCA cycle,molecule of acety-co-enzyme-A is completely oxidized and in the process CO2,H2O,NADH2,FADH2 and ATP is produced.
- TCA cycle takes place only during aerobic respiration.
- the second step in cellular respiration is TCA cycle.
- Pyruvate is converted into CO2 and H2O during TCA cycle.
- ATP molecules are not used up in TCA cycle.
- two molecules of ATP are produced in TCA cycle.
- CO2 is produced in TCA cycle.
- oxygen is required for aerobic respiration.
- aerobic respiration takes place in nucleus as well as in cytoplasm.
- at the end of aerobic respiration CO2 and H2O is formed.
- energy is produced in large amount in aerobic respiration.
- glucose is completely oxidized in aerobic respiration.
- 38 molecules of ATP are formed during aerobic respiration.
- chemical reaction:C6H12+6O2+6CO2+686 Kcal.
- oxygen is not required for anaerobic respiration.
- anaerobic respiration occurs only in the cytoplasm.
- at the end of anaerobic respiration CO2 and C2H5OH are formed.
- energy is produced in lesser amount in anaerobic respiration.
- glucose is completely oxidized in anaeerobic respiration.
- 2 molecules of ATP are formed during anaerobic respiration.
- chemical reaction:C6H12O6=2 C2H5OH + 2 CO2 + 50 Kcal.
- in mitosis the chromosome number does not change.Diploid cell remain Diploid without change.
- one cell gave rise to two daughter cells in mitosis.
- Karyokinesis of mitosis has four stages,viz.prophase,metaphase anaphase and telophase.
- Prophase of mitosis is not lenghty.
- genetic recombination does not happen in mitosis as there is no crossing over.
- mitosis is essential for growth and development.
- mitosis takes place both in somatic cells and germinal cells.
meiosis:
- in meiosis, the chromosome number is reduced to half. the diploid cells become haploid.
- one cell gives rise to four daughter cells in meiosis.
- meiosis has two major stages,viz. meiosis-I and meiosis-II. each is further subdivided into prophase, metaphase, anaphase and telophase.
- prophase of meiosis I is very lengthy.
- genetic recombination takes place in homologous chromosomes as there is crossing over during prophase-I.
- meiosis is essential for formation of gametes in sexual reproduction.
- meiosis takes place in somatic cells.
ANS: when glucose is completely oxidized in aerobic cellular respiration, it produces 38 molecules of ATP. in cellular respiration, three processes take place one after the other, these are glycolysis, Krebs cycle and electron transport chain reactions. in absence of oxygen, only glycolysis can occur but further two reactions will not take place. if glycolysis occurs in absence of oxygen, it produces alcohol. therefore, oxygen is necessary for complete oxidation of glucose.
2.Krebs cycle is also known as citric acid cycle.
ANS: sir Hans Kreb proposed this cycle and hence it is called Krebs cycle. these are series of cyclic chain reactions which begin with acetyl-coenzyme-A molecules which act with molecules of oxaloacetic acid. the reactions are catalyzed with the help of specific enzymes.
3.sometimes, higher plants and animals too perform anaerobic respiration.
ANS: when there is deficiency of oxygen in the surrounding, the aerobic respiration is not possible. in such case, to survive, higher plants switch over to anaerobic respiration. in some animals tissues in case of oxygen deficiency cells perform anaerobic respiration.
4. fibers are one of the important nutrients
ANS: fibres are indigestible substance. they are thrown out along with other useless and undigested matter. this aids in egestion. some fibers also help in the digestion of other substances. green leafy vegetables, fruits, cereals, etc are considered as important in the diet as they supply nutritious fibers.
5.Cell division is one of the important properties of cells and organisms.
ANS: cell division is very essential for all living organisms. the growth and development is possible only due to cell division. the emaciated body can be restored only through the cell division which adds new cells. offspring is produced only through the cell division that take place in parents.
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