9th Biology Chapter # 7 All Punjab Board Papers | 5 Years old Board Papers Short questions | Repeated Short questions in all Board Papers

   CHAPTER No. 7

 1.                 What is bio-energetics?                                                      

Ans:    It is the study of energy relationship and energy transformations in living organisms. 

2.                 Explain bio-energetic with the help of an example.

Ans:    Organisms obtain energy by metabolizing the food. They eat or prepare food contain potential energy in its bonds when these bonds are broken down a large amount of kinetic energy is usually released. Some of this energy is stored in the form of potential energy in the bonds of ATP molecules while the rest escapes as heat. The potential energy stored in ATP is again transformed into the kinetic energy to carry out life activities.

3.                 What is redox reaction?                 

Ans:    It is the reaction which involves exchange of electrons between atoms. If oxidation and reduction occurs at the same time it is called redox reaction.

4.                 Define oxidation and reduction./  What is meant by Reduction?                                                                                           

Ans:    The loss of electrons is called oxidation. The gain of electrons is called reduction.

5.                                   Explain that electrons can be source of energy during oxidation reduction.                                             

Ans:    During light reaction of photosynthesis the electrons are emitted first from the thylakoid membrane and then these electrons are passed through the electron transport chain also and help in the formation of energy rich molecules like ATP and NADPH.

6.                 Who discovered the ATP molecule? What is the function in cell?       

Ans:    The major energy currency of all cell is a nucleotide called adenosine triphosphate (ATP). It is main energy source for majority of the cellular function like photosynthesis of macro molecules endocytosis, exocytosis etc. It has ability to store and release energy. It was discovered in 1929 by Karl Lorhmann and was proposed to be main energy transfer molecule in the cell by the noble prize winner, Fritz Lipmann in 1941.

7.                 Which molecule is called energy currency of cell?

Ans:    ATP molecule is called energy currency of cell.

8.                 What is meant by energy currency of a cell? Explain.

Ans:    The major energy currency of all cells is a nucleotide called adenosine triphosphate (ATP). It is the main energy source for majority of cellular functions like synthesis of macromolecules (DNA, RNA and proteins) movement, transmission of nerve impulses, active transport, exocytosis and endocytosis.

9.                 What is ATP and who discover it? / When and what was discovered by Karl Lohman.                                                                               

Ans:    ATP means Adenosine triphosphate. It is the main energy source for majority of the cellular functions like synthesis of the macromolecules. It was discovered in 1929 by Karl Lohmann.

10.             Write down the three sub units of ATP.  

Ans:    1- Adenine     2- Ribose sugar                      3- Phosphate groups

 

11.             How much energy is released from one mole of ATP? 

Ans:    The breaking of one phosphate bond releases about 7.3 kcal (7300 calories) per mole of ATP.

12.             Define photosynthesis. Write raw material for photosynthesis./ Define Photosynthesis and write its equation.                         

Ans:    Photosynthesis is the synthesis of glucose from carbon dioxide and water in the presence of sunlight and chlorophyll, with oxygen as a by-product.

            Raw material for Photosynthesis is carbon dioxide, water and light energy.

13.             What is photosynthesis? And where it occurs?

Ans:    It is the synthesis of glucose from carbon dioxide and water in the presence of sunlight and chlorophyll, with oxygen as a by-product. These reactions occur in thylakoids of chloroplast.

14.             What products are produced during photosynthesis?

Ans:    Products of photosynthesis: Glucose (C₆H₁₂O₆), oxygen (O₂) and water.

15.             Why is it said that all life forms are dependent on photosynthesis?

Ans:    Photosynthesis is the most important biochemical pathway and all life depends on it. Because through photosynthesis plant make sugar for their own use and make oxygen (O₂) as by product for the use of respiration in animals.

16.             Why is Photosynthesis considered as anabolic process?

Ans:    It is an anabolic process because it is the synthesis of glucose from CO₂ and H₂O in the presence of sunlight and chlorophyll with O₂ as a by-product.

17.             Define light reactions.

Ans:    Light reaction: In these light energy is captured and is used to make high-energy molecules (ATP and NADPH).  These reactions are called light reactions and take place on the thylakoid membranes of chloroplast.

18.             What are dark reactions?                                                   

Ans:    In these reactions carbon dioxide is reduced to make glucose.  In this phase energy form high energy molecules (ATP and NADPH) is utilized. As these reaction do not use light directly, they are known as dark reaction.

19.             What is the difference between light and dark reaction?

Ans:    Light Reaction: This reaction occurs in the presence of light.

            Dark Reaction:  This reaction occurs in the absence of the light.

20.             Write any two events of dark reaction.

Ans:    1- CO₂ molecules are combined with 5-carbon compounds to form temporary 6-carbon compounds, each of which split into two 3-carbon compounds.

            2- The carbon compounds are reduced to 3-carbon carbohydrates by using ATP and hydrogen from NADPH. The 3-carbon carbohydrates are used to manufacture glucose.

            3- The 3-carbon carbohydrates are also used to regenerate the original 5-carbon compounds. This step also utilizes ATP.

21.             What are Pigments? Describe their function. Or What accessory pigments

Ans:    Pigments are the substances that absorb visible light. Different pigments absorb light of different wavelengths (Colours).

22.             Write names of photosynthetic pigment.

Ans:    Photosynthetic pigments:

1-                 Chlorophyll-a (the main photosynthetic pigment)

2-                 Chlorophyll-b            

3-                 Carotenoids

23.             What is sunlight energy? Write its function in plant.

Ans:    Sunlight energy is absorbed by chlorophyll. It is then converted into chemical energy. Which derives the photosynthetic process. The light ray of different wavelengths are not only differently absorbed by photosynthetic pigments but are also differently effective in photosynthesis. The blue and red lights carry out more photosynthesis.

24.             Describe the effect of intensity light on the speed of photosynthesis.   

Ans:    It decreases as light intensity decreases and increased as light intensity increases. However at much higher intensity, the rate of photosynthesis becomes constant.

25.             What is the role of chlorophyll in photosynthesis?

Ans:    Sunlight energy is absorbed by chlorophyll; it is then converted into chemical energy, which derive the photosynthetic process. The main chemical energy is glucose, chlorophyll-a is the main photosynthetic pigments.

26.             What is the role of pigments in photosynthesis?

Ans:    Pigments are the substances that absorb visible light.7.2.3. LIMITING FACTORS IN PHOTOSYNTHESIS:

27.            What are limiting factors in photosynthesis? Give two examples

Ans:    Any factor (absence are those) deficiency of which can decrease the rate of a metabolic reaction i.e photosynthesis. Limiting factors of photosynthesis are light intensity, temperature, concentration of carbon dioxide etc.

28.             What is the effect of CO₂ concentration on Photosynthesis?   

Ans:    Effect of CO₂ Concentration of Photosynthesis:  As CO₂ concentration rises, the rate of photosynthesis goes on increasing. Increase in CO₂ concentration beyond a certain level causes the closure of stomata and it decreases the rate of photosynthesis.

29.             What is cellular respiration and explain it.                                  

Ans:    During this process the C-H bonds are broken and water are also formed. The cellular energy yielding process is called cellular respiration.

30.             Differentiate between photosynthesis and respiration.          

Ans:   

Photosynthesis	Respiration
It is the synthesis of glucose from carbon dioxide and water in the presence of sunlight and chlorophyll with oxygen as a by-product.	During this process the C-H bonds are broken down by oxidation-reduction reaction. So carbon dioxide and water are formed. The cellular energy yielding process is called cellular respiration.

31.             Write down names of two compounds produced during respiration.

Ans:    During respiration compound are produced: Carbon dioxide (CO₂), water (H₂O) and energy.

32.             Write two differences of Aerobic and Anaerobic Respiration?/ Define aerobic and anaerobic respiration./ Define anaerobic respiration.

Ans:   

Aerobic Respiration	Anaerobic Respiration
It occurs in the presence of O2	It occurs in the absence of O2
Glucose molecule is broken down into two molecules of pyruvic acid (3-C)	Glucose is incompletely oxidized with less amount of energy released. Glucose molecule is broken down to two puruivc acid molecule (3-C)
The molecule of pyruvic acid are completely oxidized to CO2 and H2O. All energy is released.	The pyruvic acid is transformed into ethyl alcohol or lactic acid. Many of the C-H bond are left unbroken in products.

33.             Define aerobic respiration and write its equation.

Ans:    Aerobic respiration: In the presence of oxygen complete oxidation of glucose occurs with maximum release of energy. A molecule of glucose is broken down into two molecules of pyruric acid.

34.             Define lactic acid fermentation.                            

Ans:    In this type of anaerobic respiration, each pyruvic acid molecule is converted into lactic acid (C₂H₆O₃).

35.             Define alcoholic fermentation.                             

Ans:    In this type of anaerobic respiration, pyruvic acid is further broken down to alcohol,  C₂H₅OH and CO₂.

36.             What is meant by anaerobes?

Ans:    Some organisms including some bacteria and some fungi get energy from anaerobic respiration and are called anaerobes.

37.             What is importance of aerobic and anaerobic respiration?/What is significance of anaerobic.

Ans:    Importance of aerobic respiration:

1- In the presence of oxygen, complete oxidation of glucose occurs with maximum release of energy.

            Importance of aerobic respiration:

2- Human can provide energy to their skeletal muscle cells through anaerobic respiration.

3- The fermenting powers of bacteria are used for making cheese and yogourt.

38.             Define Glycolysis? Where does process occur?             

Ans:    It is a process in which Glucose (6-C) molecule is broken into two molecules of pyruvic acids (3-C) it occurs in cytoplasm.

39.             What is meant by Krebs cycle?                                         

Ans:    In Krebs cycle, the pyruvic acid molecules are completely oxidized, along with the formation of ATP, NADH and FADH_2. Before entering in Krebs cycle, pyruvic acid is changed into a 2-carbon compound called acetyl-CoA.

40.             What do you know about electron transport chain?

Ans:    Electron transport chain is the final step of cellular respiration. It is the transfer of electron on an electron transport chain. In this step NADH and FADH₂ release electrons and hydrogen ions. These electrons are taken up by a series of electron carriers. When electron move through the series of electron carriers they lose energy which is used to synthesized ATP. At the end of chain, electrons and hydrogen ions combine with molecular oxygen and form water.

41.             What does FAD stand for?

Ans:    Flavin adenine dinucleotide (FAD is also coenzymes like NAD⁺. It gets 2 hydrogen and reduces to FADH₂

42.             What is respiration energy budget? Give example.

Ans:    During anaerobic oxidation of glucose molecule only 2 ATP molecules are gained as the net profit while during aerobic respiration 36 ATP modules are produced as profit.

43.             How many ATP are formed from NADH and FADH₂?

Ans:    Each NADH produces 3 ATP in electron transport chain. The NADH generated in glycolysis gives 2 ATP because 1 ATP is spent to transport it across the mitochondrial membrane.

            Each FADH₂ produces 2 ATP.