Dear students, prepare for biology class 9th chapter 7 long questions. These important long questions are carefully added to get you best preparation for your 9th class biology ch. 7 exams.
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Question: 1
How would define bioenergetics while relating it to the oxidation-reduction reactions in the living systems?
(b)How electrons add as a energy source?
Answer: 1
1-20
Question: 2
Which phenomenon are involved in the intake of CO, and water by plants?
Answer: 2
2-20Ans. (a) Photosynthesis:
Definition:
The process by which plants and some other autotrophic organisms prepare their food (glucose) in the presence of sunlight and chlorophyll, with oxygen as a by-product is called photosynthesis.
Importance:
Photosynthesis is an anabolic process and is an important component of bioenergetics in living systems. It is the most important bio-chemical pathway and nearly all life depends on it.
Occurrence:
Photosynthesis occurs in plants, protists (algae) and some autotrophic bacteria.
Chemical Equations:
The chemical equation representing the process of photosynthesis is as follows;
ll hy
6CO2 + 12H20 + Light energy Chlorophyll vv An
2 + 6H20
Ans. (b) Intake of water and CO2 for Photosynthesis:
Water and CO2 are the raw materials of photosynthesis. The plants have mechanisms for the intake and transport of these materials.
Intake of water
Water present in soil is absorbed by roots and root hairs through osmosis. This water is eventually transported to leaves through xylem vessels.
(After the entry of water in the inner cells of the root, it reaches xylem vessels). (ii) Intake of CO2:
The air that enters the leaf through tiny pores (stomata) reaches into the air spaces present around mesophyll cells.
This air carries CO2 which gets absorbed in the thin layer of water surrounding the mesophyll cells. From here, the CO2 diffuses into the mesophyll cells.
Question: 3
Describe the mechanisim of photosynthesis in detail.
Answer: 3
3-20
Question: 4
Define respiration?Describe its types and importance.
Answer: 4
4-20
Question: 5
Describe the machanism of respiration.
Answer: 5
5-20Ans. Mechanism of respiration
The process of respiration involves complex series of reactions. For the study of all the reactions of glucose oxidation, we will. Study the mechanism .of aerobic respiration. Aerobic respiration is a continuous process but we can divide into three main stages.
(i) Glycolysis
(ii) Krebs cycle
(iii)Electron Transport chain
(i) Glycolysis
Location:
Glycolysis occurs in cytoplasm and oxygen is not involved at this stage so it occurs both in aerobic and anaerobic respiration.
Definition:
The process in which glucose molecule is broken into two molecules of pyruvic acids (3c).
(ii) Krebs’s cycle
Discovery a British biochemist, Sir Hans Krebs discovered this series of reactions that is why it is called the Krebs cycle •
Definition: In Krebs cycle, pyruvic acid molecules are completely oxidized along with the formation of ATP, NADH and FADH2.
Before entering in Krebs cycle, pyruvic acid is changed into a 2- carbon compound called acetyl COA.
(iii)Electron Transport chain
It is the final step of cellular respiration. It is the transfer of electron in an electron transport chain. In this step,
i. These electrons are ‘taken up by a series of electron carriers.
ii. When electrons move, through the series of electron carriers they lose energy, which is used to synthesize ATP.
iii. At the end of chain, electrons and hydrogen ions combine with molecular oxygen and form water.
iv. NADH and FADH2 release electrons and hydrogen ions.
Question: 6
Describe Energy Budget of respiration.
Answer: 6
6-20
Question: 7
Q no 7 (A) Define Bioenergetics and explain <gwmw class="ginger-module-highlighter-mistake-type-3" id="gwmw-15862385860586819682717">oxidation reduction</gwmw> in detail.
Answer: 7
7-20Oxidation-Reduction Reaction
Explain limiting Factor in photosynthesis?
Any enviromental factor the absence or deficiency of which can decrease the rate of metabolic reaction is called limiting factor for that reaction. Many factor like light intensity, temperature, concentration of carbon dioxide and availability of water act as limiting factor for synthesis
Effect of light intensity and temperature.
The rete of photosynthesis veiwes with light intensity. It decrease as light intensity decrease and increase as intensity decreas and increase as intensity increase. However at much higher light intensity. the rate of photosynthsis becomes constent .
The rate of photosynthesis decrese with decrease in temperatura . It increase as tempertura is increase over a limited randge but if light intensity is law .
Effect of carbon dioxide concentration:
As carbon dioxide concentration rises the rate of photosynthesis goes on increasing until limited by other . factor . increase in carbon dioxide concentration beyond a certain level causes the closure of stomata and it decrease the rate of photosynthesis.
Question: 8
Q no: 6<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15862441812846204700572">(</gwmw>A) What is the role of chlorophyll and light in photosynthesis?
Answer: 8
8-20Sunlight energy is absorbed by chlorophyll. It is then converted into chemical energy. Which drives the photosynthesis processonly about one present of the light failing on the leaf surface is absorbedthe rest is reflected to transmitted the light rays of different wavelengths are not only differentwavelengths are not only different absorbed by photosynthetic pigments are also different effective in photosynthesis.
The blue and red light carries out moresynthesis- photosynthetic pigments are organizedin the form clustercalled photosystem in the lastmembrane of chloroplasts chlorophyll-a is the main photosynthetic pigments other are called accessory pigments and include chlorophyll -b and carotenoids chlorophyllsabsorb mainly blue and red lights. Same wavelength not absorbedby chlorophyll`a ' are very effectively absorbed by accessory pigments and vice- varse .
Question: 9
Q no 6 (B) Write a <gwmw class="ginger-module-highlighter-mistake-type-2" id="gwmw-15862443558537267001081">not</gwmw> on Mechanism of Respiration:
Answer: 9
9-20The process of respiration involves complex series of reaction. For the study of all reaction of glucose oxidation. we will go into the mechanism of aerabic respiration. Aerabic respiration is continueus process but for convenience we can divide it into three main stagesGlycolysis :Electro transport chain: is the final step of cellular respiration Itis the transfer of electronon an electron transport chain. In this step NADH and FADH2release electrons and hydrogenions. these electrons are taken up by a seriesof electron caries they lose energy. which is used by synthesis Atp at the end of chain electrons and hydrogen ions combine with molecular oxygen and form water
1- glycolysis 1- krevs cylcle and 3- electron transport chain.
Occur in aytoplasm and oxygen is not involved in this stages . That is why it occure in both types of respiration aerobicand anaerobic. In krebs cysle , the pyruvic acid molecules are completely oxidized along with the formation of ATP , NADH , FADH2. Before entering in krebscycle , pyruvicacid is changed into a 2- carbon compound called acetyl-coA.
Question: 10
Q no: 7<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15862456447886811045789">(</gwmw>A) State how the varying light intensity, carbon dioxide concentration and temperature affect the rate of photosynthesis?
Answer: 10
10-20Effect of light intensity and temperature.
The rate of photosynthesis varies with light intensity it decrease light intensity decrease and increase as intensity increase. However, at much higher light intensity the rate of photosynthesis becomes constant .
The rate of photosynthesis decrease with decrease in temperature, it increase as temperature is increase over a limited range But if light intensity is law . Increasing the temperature has little on the rate of photosynthesis.
Effect of Carbon dioxide concentration
As carbon dioxideconcentration rises the rate of photosynthesis goes on increase untillimited by another factor increasesin carbon dioxide concentration beyond a certain level causes the closureof stomata and it decrease the rate of photosynthesis
Question: 11
Q no: 7<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15862456447886811045789">(</gwmw>A) State how the varying light intensity, carbon dioxide concentration and temperature affect the rate of photosynthesis?
Answer: 11
11-20Effect of light intensity and temperature.
The rate of photosynthesis varies with light intensity it decrease light intensity decrease and increase as intensity increase. However, at much higher light intensity the rate of photosynthesis becomes constant .
The rate of photosynthesis decrease with decrease in temperature, it increase as temperature is increase over a limited range But if light intensity is law . Increasing the temperature has little on the rate of photosynthesis.
Effect of Carbon dioxide concentration
As carbon dioxideconcentration rises the rate of photosynthesis goes on increase untillimited by another factor increasesin carbon dioxide concentration beyond a certain level causes the closureof stomata and it decrease the rate of photosynthesis
Question: 12
Q no: 7 (B) Explain Aerobic and anaerobic respiration in detail.
Answer: 12
12-20The most common food used by cell to get energy by cellular respiration is glucose. The way glucose oxidized depend on the detail validity of oxygen. The cellular respiration occuring in the presence of oxygen is called aerobicrespiration while the one occur in the absense of oxygen is called anaerobic respirationpyruvic acid _____> Ethyl Alcohol + Carbon dioxidelactic acid:Pyruvic acid _____> lactic acid
Aerobic Respiration:
In the presence of oxygen complete oxidation of oxygen complete oxidation of glucoseoccur with maximum release of energy. In the first phase of aerobicrespiration a molecule of glucose (6-c) is broken down into two molecule of pyouvic acid.In the second phase molecule of pyruvic acid arecompletely oxidized to co 2and water and all energy is released The overall reaction is a fallows
C6H12O6 = 6O________> 6CO2 + 6H2O Energy Anaerobic Respiration:
In the absence of oxygen, glucose in incompletely oxidized with less amount of energy released. In an anaerobicrespiration. The first phase is exactly similar to that of aerobicrespiration. A molecule of glucose is broken down into two molecule of pyruvic acid . But in the second phase pyruvic acid is not completely oxidized it is transformed intoehyl alcohol or lucidacid. In this way of the C-H ponds are left unbroken in the products Anaerobic respiration is further classified as alcoholismfermentation and lactic acid.
Alcoholic fermentation:
It occur in bacteria yeast etc. in this type of enaerabic respiration pyruvicacid is further broken down into alcohol. ( C2H5OH) and Co2
It occurs in skeleton muscles of humans and other animals during extreme physical activities. This also happen in the bacteria present in milk. This type of aerabic respiration. each pyrucic acid molecule is coverted into lactic acid (C2H6O5)
Question: 13
Q no5 (B) Explain Limiting factors in photosynthesis
Answer: 13
13-20Any environmentalfactor the absence or deficiency of which can decrease the rate of metabolic reaction is called limiting factor for that reaction Many factor like light intensity, temperature, concentration of carbon dioxide and availabilityof water act as liming factor for synthesis.limited by other factor increase in carbon dioxide concentrationbeyond a certain level causes the closure of stomata and it decrease the rate of photosynthesis.
Effect of Light Intensity and Temperature:
The rate of photosynthesis varies with lightintensity. It decrease as light intensity decrease and increase as intensityincrease however at much higher light intensity, The rate of phatosynthesis becomes constant.
The rate of photosynthesis decrese with decrease in temperature . It incresase as temperature is increase over a limited range . But If light intensity is low.
Effect of carbon Dioxide concentration:
As carbon dioxide concentration rise the rate of photosynthesis goes on increasing unit.
Question: 14
Write the summary of light reaction
Answer: 14
14-20Light reaction / Z-scheme : During light reaction phase , light energy is captured and is to make high energy molecules (ATP and NADPH) .Theses reactions ,which are known as light reaction
Question: 15
Write a note on dark reaction .(Calvin cycle )
Answer: 15
15-20Dark reactions were discovered by Malvin Calvin and his colleagues at the university of California . Calvin was awarded noble prize in 1961 for his work on photosynthesis
During this phase , CO2 is reduced to make glucose and energy from high energy molecules (ATP and NADPH) is utilized , since these reactions do not use light directly, they are known as dark reaction
Location : Dark reaction takes place in the stroma of the chloroplast
Question: 16
What is the role of chlorophyll and light in photosynthesis ? Explain limiting factors in photosynthesis
Answer: 16
16-20Role of light : Sunlight energy is absorbed by chlorophyll . It is then converted into chemical energy . This derives the photosynthetic process . Only about 1 % of the light falling on the leaf surface is absorbed , the rest is reflected or transmitted . The light rays of different wavelengths are not only differently absorbed by photosynthetic pigments but are also differently effective in photosynthesis
Question: 17
Define respiration and gives its types
Answer: 17
17-20Respiration : In this process the C-H bonds are broken by oxidation-reduction reaction and so carbon dioxide and water are also produced , this cellular energy-yielding process is called respirationExplanation : When we burn a fuel , it utilizes oxygen and yields energy in the form of light , heat etc . In this burning process , oxygen is used to break the C-H bonds present in the food in their cells . This break down yields energy which is transformed into ATP . During this process the C-H bonds are broken by oxidation-reduction reaction and so carbon dioxide and water are also produced . The cellular energy -yielding process is called respiration
Question: 18
What is importance of anaerobic respiration ?
Answer: 18
18-20Importance of fermentation : When life evolved on the earth , the early land or water habitats did not have any supply of free oxygen (O2) . In these anaerobic conditions , early organisms respired and got energy for their life activities
Anaerobes : Some organisms including some bacteria and some fungi get energy from anaerobic respiration and are called anaerobes
Question: 19
Define nutrition and nutrients and explain types of organisms on the basis of nutrition
Answer: 19
19-20Nutrition:
The process in which food is obtained or prepared ,absorbed and converted into body substances for growth and energy is called nutrition
Or
Nutrients :
The substances acquired by organisms to obtains and use for energy are called nutrients
OR
Nutrients are the elements and compounds that an organism obtained and uses for energy or for synthesis of new materials
Question: 20
Explain mineral nutrients in plants ?
Answer: 20
20-20Plants have the most efficient mechanisms for autotrophic mode of nutrition . Plants gets carbons , hydrogen and oxygen from carbon dioxide and water . In addition to these elements plants also require mineral elements for various activities and structures
Carnivores plants have evolved mechanisms for trapping and digesting small animals . The products of this digestion are used to supplement the plant 's supply nitrogen
