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We can divide cellular respiration into three metabolic processes: Glycolysis, the Krebs cycle, and oxidative phosphorylation. Each of these occurs in a specific region of the cell. 1. Glycolysis occurs in the cytosol. The 6-carbon sugar, glucose (c6H12O6), is broken down into two molecules of a 3-carbon molecule(c3H14O3) called pyruvate . This change is accompanied by a net gain of 2 ATP molecules and 2 NADH molecules. 2. The Krebs cycle takes place in the matrix of the mitochondria. Pyruvate is transported into the mitochondria and loses carbon dioxide to form acetyl-CoA (Acetyl coenzyme), a 2-carbon molecule. When acetyl-CoA is oxidized to carbon dioxide in the Krebs cycle, chemical energy is released and captured in the form of NADH, FADH2, and ATP. 3. Oxidative phosphorylation via the electon transport chain is carried out on the inner mitochondrial membrane. The electron transport chain allows the release of the large amount of chemical energy stored in reduced NAD+ (NADH) and reduced FAD (FADH2). The energy released is captured in the form of ATP (3 ATP per NADH and 2 ATP per FADH2). Note: In the absence of oxygen, respiration consists of two metabolic pathways: glycolysis and fermentation. Both of these occur in the cytosol. Fermentation complements glycolysis and makes it possible for ATP to be continually produced in the absence of oxygen. By oxidizing the NADH produced in glycolysis, fermentation regenerates NAD+, which can take part in glycolysis once again to produce more ATP. Each molecule of glucose can generate 36-38 molecules of ATP in aerobic respiration but only 2 ATP molecules in respiration without oxygen (through glycolysis and fermentation). You have remembered that in cell, Cytosol is the fluid portion of a cell's cytoplasm, which lies outside the organelles and other insoluble components of the cytoplasm Class 10 Biology Chapter_Life Process Read
Here you will get Life Process CBSE Test Paper with solution- 01 Life Process CBSE Test Paper with solution-02 Life Process CBSE Test Paper with solution-03 Life Process CBSE Test Paper with solution-04 Life Process CBSE Test Paper with solution-05 Class 10 science Quick Revision Life Processes Visit page. For more : see post 10th Biology: HEREDITY AND EVOLUTION SOLVE 1. “Different species use different strategies to determine sex of a new born individual. It can be environmental cues or genetically determined‟. Explain the statement by giving example for each strategy. Ans: Environmental Cue – (a) In some animals, the temperature at which fertilized eggs are kept determines whether the developing animal in egg is male or female eg lizard (b) In some animals like snail, individual can change sex. Genetically – A child who inherits an x chromosome from her father will be a girl and one who inherits a y chromosome from the father will be a boy. 2. a. Define the term Gene. b. The gene for red hair is recessive to the gene for black hair. What will be the hair colour of a child if he inherits a gene for red colour from his mother and a gene for black hair from his father? Express with the help of flow chart. Ans: a. The functional unit of DNA which are made of nucleic acids and protein is called gene. b. Given Black hair – father Dominant [ BB ] and Red hair – Mother – Recessive [ bb] Parents Father BB/Bb X Mother Bb/bb F1 Bb (Black) 3 .a. Mention any two point of difference between acquired and inherited traits. b. If the tail of a mouse is cut for twenty one generations, will the tail occur in the twenty second generation of that mouse? Give reason to support your answer. c. Define the term – Natural Selection. Ans: a. Acquired Traits Inherited Traits Trait acquired during its lifetime Traits inherited from its parents cannot passed on to progeny passed on to progeny Not present in the genetic makeup Present in the genetic makeup b. The mouse continue to have information for presence of tail in its DNA So, mouse will continue to have tail, because it is an acquired trait. c. The process by which nature selects organisms which are more suitably adapted and possesses favourable variations is called Natural Selection 4. With regard to turnip, carrot, sweet potato and potato, three belong to the same category. Identify those three modifications and mention whether they are homologous or analogous. Also mention the reason why the fourth modifications do not belong to the same category. Ans: Turnip, Carrot, Sweet Potato – are modified root – Homologous organs but Potato – modified stem. 5. What are chromosomes ? Explain how in sexually reproducing organisms the number of chromosomes in the progeny is maintained Ans: Chromosomes are thread like structures made up of DNA found in the nucleus of cell. The original number of chromosomes becomes half during formation of gamete. Hence, when the gametes combine, the original number of chromosomes gets restored in the progeny. 6. Explain with an example for each, how the following provides evidences in favor of evolution in organisms: (a) Homologous organs (b) Analogous organs (c) Fossils Ans: Homologous organs – Study of homologous organs suggests that the organs having same structure but performing different functions have evolved from a common ancestor. Ex. - forelimbs of a frog, lizard, bird and man. Analogous organs – Study of Analogous organs suggests that these organs are having different origin and structural plan but perform same function . These are evolved from different ancestors and show adoption of organs for common use. Ex. – wings of butterfly and wings of bat. Fossils – provide the missing links between two species. Fossil Archaeopteryx possess features of reptiles as well as birds. This suggests that birds have evolved from reptiles 7. Explain the following: (a) Speciation (b) Natural Selection Ans: Speciation – The process by which new species develop from the existing species is known as speciation. Speciation takes place when variation is combined with geographical isolation. Natural selection – this is the change in frequency of some genes in a population. This give survival advantage to a species from elimination. Ex. – in a population of beetles, a new variation (green colour) get survival benefit / advantage to green beetles whereas other (red) perishes. 8. How do Mendel’s experiments show that the (a) traits may be dominant or recessive, (b) traits are inherited independently ? Ans: a) When Mendel cross pollinated pure tall pea plants with pure dwarf pea plants, only tall plants were obtained in F1 generation. On self pollinating the F1 progeny, both tall and dwarf plants appeared in F2 generation in the ratio 3:1 Appearance of tall character in both the F1 and F2 shows that it is a dominant character. The absence of dwarf character in F1 generation and its reappearance in F2 shows dwarfness is the recessive character. b) When Mendel conducted a dihybrid cross having two sets of characters, he obtained only one set of parental characters in F1 generation whereas in F2 generation he obtained both the set of parental characters now recombined in the ratio of 9:3:3:1. The appearance of new recombinants in the F2 generation along with parental type shows that traits are inherited independently. 9. What do you mean by Gene flow, Genetic drift . Ans: Gene flow is transfer of gene between population that are partly but not completely separated. Genetic drift: It is the random change in the frequency of alleles (gene pair) in a population over successive generations. Genetic drift takes place due to (a) Severe changes in the DNA (b) Change in number of chromosomes 10. ‘‘It is possible that a trait is inherited but may not be expressed.’’ Give a suitable example to justify this statement. Ans: Yes, it is possible. Example – When pure tall pea plants are crossed with pure dwarf pea plants, only tall pea plants are obtained in F1 generation. On selfing tall plants of F1, both tall and dwarf plants are obtained in F2 generation in the ratio 3:1. Reappearance of the dwarf character, a recessive trait in F2 generation shows that the dwarf trait/ character was present in individuals of F1 but it did not express (due to the present of tallness, a dominant trait / character). 11. ‘‘It is a matter of chance whether a couple will have a male or a female child.’’ Justify this statement by drawing a flow chart. Ans: A human male has XY sex-chromosomes and produces two types of sperms (heterogametic). Either with X-chromosome or with Y-chromosome. A human female has XX sex-chromosomes and produce ova of one type (homogametic) all with X-chromosomes. Parents Male Female Gametes X Y XX Progeny XX XY Female (50%) Male (50%) 12. What is speciation? List four factors that could lead to speciation. Which of these cannot be a major factor in the speciation of a self-pollinating plant species? Explain. Ans: Speciation is the process of the formation of new species from pre-existing ones. Factors – (i) Mutations (ii) Natural selection (iii) Genetic drift (iv) Geographical Isolation Geographical isolation cannot be a major factor in the speciation of a self pollinating plant species. This is because physical barrier cannot be created in self pollinating plants. 13. (a) Cite the evidence on the basis of which it is concluded that birds have evolved from reptiles. (b) Insects, Octopus, Planaria and Vertebrates also possess eyes. Can these animals be grouped together on the basis of the eyes they possess. Why or why not ? Give reason to justify your answer. Ans: a) i) Fossils showing imprints of feathers along with the bones in dinosaurs / reptiles found, ii) They could not fly and presumably using the feathers for insulation, iii) Later they developed / evolved and adapted feathers for flight. iv) Thus, they give evidence that birds have evolved from reptiles. b) No, the structure of the eye in each of these organisms is different / they have separate evolutionary origins. 14. How does sexual reproduction leads to similarities as well as variations ? Ans: Similarities and variations are dependent on the type of allele combination an offspring will get from their parents. If a child get dominant alleles from father then he will look quite similar to his father and quit different from his mother. If he got a combination of dominant alleles from both the parents then he will be quite different from both the parents. 15. What is hybrid? Give term for (i) externally exhibited traits (ii) Traits developed by gene - Ans: Organism having two or more mixed traits are called hybrid . Plants having two pairs of contrasting characters is called dihybrid. (i) Externally exhibited traits : Phenotype (ii) Traits developed by gene – Genotype Visit page dedicated Board exam Heredity and evolution 1 MARKS QUESTIONS
1. A farmer floods his field everyday thinking that watering in this manner will result a better yield of his wheat crop. What will be the result of this action of the farmer. Ans.This will result in water logging of the soil due to which roots cannot breathe and ultimately plants will die . 2. Name the term for transport of food from leaves to other parts of plants. Ans.Translocation 3. Which pancreatic enzyme is effective in digesting proteins? Ans.Trypsin 4. Which enzyme is present in saliva breaks down starch? Ans.Salivary amylase. 5. After a vigorous exercise you may experience cramps in your leg muscles. Why does this happen? Ans.Accumulation of lactic acid 6. Name the organelle in which photosynthesis occurs. Ans.Chloroplast. 7. Name the type of blood vessels which carry blood from organs to the heart. Ans.Veins. 8. Name the respiratory structures of i.Mosquito ii)earth worm. Ans.i) mosquito—System of air tubes. ii)earth worm—moist skin. 9. Write the two functions of kidneys. Ans. Osmoregulation and excretion. 10. What are spiracles. Ans The holes found on the lateral side of insect‘s body.X 1 MARKS QUESTIONS
1. A farmer floods his field everyday thinking that watering in this manner will result a better yield of his wheat crop. What will be the result of this action of the farmer. Ans.This will result in water logging of the soil due to which roots cannot breathe and ultimately plants will die . 2. Name the term for transport of food from leaves to other parts of plants. Ans.Translocation 3. Which pancreatic enzyme is effective in digesting proteins? Ans.Trypsin 4. Which enzyme is present in saliva breaks down starch? Ans.Salivary amylase. 5. After a vigorous exercise you may experience cramps in your leg muscles. Why does this happen? Ans. Accumulation of lactic acid 6. Name the organelle in which photosynthesis occurs. Ans.Chloroplast. 7. Name the type of blood vessels which carry blood from organs to the heart. Ans.Veins. 8. Name the respiratory structures of i.Mosquito ii)earth worm. Ans.i) mosquito—System of air tubes. ii)earth worm—moist skin. 9. Write the two functions of kidneys. Ans.Osmoregulation and excretion. 10. What are spiracles. Ans The holes found on the lateral side of insect‘s body. 2 marks questions answer 1.Differentiate autotrophs and heterotrophs. Ans.The organism which prepare their own food are called autotrophs for eg: green plants . The organisms which depend on the food prepared by other organisms are called heterotrophs for eg: animals 2.Differentiate between aerobic respiration and anaerobic respiratrion. Ans. Aerobic respiration It occurs in the presence of oxygen Glucose is completely broken down to carbon dioxide and water. More energy is released 38 ATP. Anaerobic respiration It occurs in the absence of oxygen. Glucose is incompletely oxidised to ethanol or lactic acid Less energy is produced 2ATP 3. Explain the role of the following in the process of digestion in the human body A) saliva B) trypsin Answer: a) Saliva contains an enzyme salivary amylase which digests starch b) trypsin.-helps in digestion of proteins. 4. What is double circulation.? Ans..In double circulation blood goes through the heart twice during each cycle in vertebrates. 5 Write any two points of difference between respiration in plants and respiration in animals. Respiration in plants.
Respiration in animals
6 Differentiate Holozoic nutrition and saprophytic nutrition. Answer: Holozoic nutrition In this nutrition organisms derive their food by consuming complex organic materials by the process of ingestion and then converting the complex molecules into simpler ones to obtain nutrients. Eg. animals and human beings. Saprophytic nutrition In this type of nutrition organism derive their food from the dead and decaying materials. Eg.fungi 7. Why do veins have thin walls compared to arteries? Ans: Veins do not have thick walls because blood is no longer under pressure but blood emerges from the heart under high pressure. So arteries have thick walls 8. Where do the plants get each of the raw materials? a) CO2 b) water c) minerals Ans. a) CO2 from air, b)water-from soil c)minerals-from soil along with water. 9. What do the following transport? a)xylem b phloem c) pulmonary vein d) venacava Ans. a) xylem-water and minerals b) phloem- prepared food. c) Pulmonary vein-oxygenated blood d) vena cava -deoxygenated blood 10. Write one function each of the following components of transport system in human beings. a)arteries b) veins c)capillaries ans: (a) arteries- carry blood from heart to different parts of body (b) veins-carry blood from different parts of body to the heart. c) Capillaries-exchange of material between blood and surrounding cells. 11. a) How is fat digested in our body? b) Where does this take place? Ans. A) fats are emulsified by bile salts. The emulsified fats are acted upon by pancreatic and intestinal lipase to form fatty acids and glycerol. b) digestion of fats occurs in small intestine. 3 MARKS QUESTIONS 1. What is the function of epiglottis in man? Draw a labeled diagram showing the human respiratory system. Epiglottis. It is an adjustable flap of fibro cartilage that covers glottis when food is being swallowed. Diagram of human reaspiratory system. Fig 6.9 (NCERT text book page no.104.) 3. What is known as double circulation Briefly explain the process . Ans.It is passage of the same blood twice through the heart first on the right side, then on the left side in order to complete one cycle. It has two components ,pulmonary circulation and systemic circulation. Hint. pulmonary circulation and systemic circulation 4.How water is transported upwards in plants? Answer: Transpiration in leaves creates pull force and osmosis creates push fore. These two forces together helps in the movement of water and minerals dissolved the leaves. 5. Name the tissue that transports the prepared food in plants . Explain the mechanism of transport of food in plants. Ans.: phloem Hint: translocation using energy from ATP. 6Briefly describe the excretory system in human beings. Hint a pair of kidneys a pair of ureters,a urinary bladder and a urethra. 7. Describe the functioning of nephrons. Ans: Functioning of Nephron (i). Filtration: Filtration of blood takes place in Bowman’s capsule from the capillaries of glomerulus. The filtrate passes into the tubular part of the nephron. This filtrate contains glucose, amino acids, urea, uric acid, salts and a major amount of water. (ii) Re-absorption: As the filtrate flows along the tubule useful substances such as glucose, amino acids, salts and water are selectively re-absorbed into the blood by capillaries surrounding the nephron tubule. The amount of water re-absorbed depends on the need of the body and also on the amount of wastes to be excreted. (iii) Urine: The filtrate which remains after re-absorption is called urine. Urine contains dissolved nitrogenous waste, i.e. urea and uric acid, excess salts and water. Urine is collected from nephrons by the collecting duct to carry it to the ureter. 8.What are the differences between the transport of materials in xylem and phloem hint transport in xylem: Ans: water transport using transpirational pull Transport in phloem: food, transport using energy from ATP 9. Lymph is another type of fluid involved in transportation. Justify the statement by two reason. Ans: 1. It drains tissue fluid from the extra cellular space back into blood. 2. it takes lymphocytes and antibodies from the lymph nodes to the blood. 3. Some of the fluid from digestive tract is absorbed in the lymph and store the fluid Temporarily. 10. differentiate between osmoregulation and excretion excretion is the elimination of metabolic waste products from the body. Ans: Osmoregulation is regulating osmotic pressure of the body fluids by controlling the amount of water and salts in the body 11. What is the function of liver in human body ans. : Liver. Secretes bile that emulsifies fats . Bile provide alkaline medium for digestion of proteins. For more study visit Life process extra score |
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