Explore NCERT Solutions

Chapter-review: 

---

• The processes which together perform for maintenance job are
  life processes.
• Since these maintenance processes are needed to prevent damage
  and break-down, energy is needed for them.
• Multicellular organisms have specialised tissue for different jobs like transportation, excreation and digestion etc. 
• Outsidee raw materials are carbon dioxide and water that are used by organisms. 
• The proccess by which organisms take their food and get energy for life process is known as nutrition. 
• There are two types of nutrition: (i) Autotrophic nutrition (ii) Hetrotrophic nutrition. 
• There are three types of Hertrotrophic nutrition: (i) Saprophytic nutrition (ii) Holozoic Nutrition (iii) Parasitic nutrition.
• The nutrition in which organisms make their own food itself by the photosynthesis is called autotrophic nutrition. 
• The nutrition in which organisms take their food by autotrophs or other sources is known as hetrotrophic nutrition. 
• Holozoic nutrition: Animals take in solid food and breakdown or obsorb it inside the body. Amoeba and animals. 
• Saprophytic nutrition: The nutrition in which organisms feed on dead and decaying materials. Like bacteria and Moosrooms etc. 
• Paracytic nutrition: Some organisms live inside or outside of other organisms which is called host and derive ntrition from host. Like Tape worms, Lice in animals and cuscuta in plants. 
• Amoeba move with the help of pseudopodia (extension of cell
  membrane).
• Amoeba digests food in the food vacuole. 
• The human digestive system comprises of alimentary canal and associated digestive glands.
• The pancreas secretes pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.
• The inner lining of the small intestine has numerous finger-like projections called vill.
• The process takes place in the presence of air (oxygen), it is called aerobic respiration.
• The process takes place in the absence of air (oxygen), it is called anaerobic respiration.
• The energy released during cellular respiration is immediately used
  to synthesise a molecule called ATP.
• Blood is a fluid connective tissue.
• The body temperature depends on the temperature in the environment.
• The biood goes through the heart twice during each cycle in other vertebrates. This is known as double circulation.
• The force that blood exerts against the wall of a vessel is called blood pressure.
• The pressure of blood inside the artery during ventricular systole (contraction) is called systolic pressure.
• The pressure in artery during ventricular diastole (relaxation) is called diastolic pressure.
• The normal systolic pressure is about 120 mm of Hg and diastolic pressure is 80 mm of Hg.
• Blood pressureis measured with an instrument called sphygmomanometer.
• The smallest vessels have walls which are one-cell thick and are called capillaries.
• Lymph is another type of fluid also involved in transportation. This is
  called lymph or tissue fluid.
• Each kidney has large numbers of these filtration units called nephrons.

Text-book Questions

---

Page no. 95

Q1. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?

Ans: In multicellular organisms sufficient amount of oxygen cannot be carried to every part of the body by diffusion. Oxygen is very essential in multicellular organisms. The structure of multicellular organisms is very complex. So every organ needs oxygen. which cannot complete the diffusion process.

Q2. What criteria do we use to decide whether something is alive?

Ans: Living things move continuously. Even if they are in a dormant state. Outwardly they appear unconscious. Their molecules remain in motion. This gives proof of their existence.

Q3. What are outside raw materials used for by an organism?

Ans: Organisms require additional raw material from outside for physical growth. Life on Earth is based on carbon molecules. Therefore, this food item is dependent on carbon. These organic compounds are another form of food. In these the exchange of oxygen and carbon-dioxide is prominent. Apart from this, there are other water and mineral salts. Starch is formed in the presence of sunlight along with these raw materials.

Q4. What processes would you consider essential for maintaining life?

Ans: Many biological activities are necessary for the maintenance of life such as: nutrition, movement, respiration, growth and excretion.

Page no. 101

Q1. What are the differences between autotrophic nutrition and heterotrophic nutrition?

Ans :

Autotrophic nutrition: - When green plants make their own food in the presence of chlorophyll and sunlight, using CO₂ and water. This process is called photosynthesis.

Heterotrophic Nutrition:- When organisms do not make their own food but depend on others for their food, then they are called heterotrophs. For example fungus, human.

Q2. Where do plants get each of the raw materials required for photosynthesis?

Ans:

Water - The roots of the plant get water from the ground.

Carbon dioxide - Plants get it from the atmosphere through stomata.

Chlorophyll - Green leaves have chloroplasts, in which chlorophyll is present.

Sunlight - received by the Sun.

Q3. What is the role of the acid in our stomach?

Ans: Hydrochloric acid is present in our stomach. This acid forms acidic medium in the stomach. With the help of this, the enzyme performs its function. HCl acid destroys the microbes present in our food. HCl acid helps in digestion of food in the stomach.

Q4. What is the function of digestive enzymes?

Ans: Digestive enzymes convert complex food into simple, subtle and beneficial substances. In this way simple substances are absorbed by the small intestine.

Q5. How is the small intestine designed to absorb digested food? 

Ans: The digested food is absorbed in the small intestine. There are thousands of microscopic, angular-like villous in the small intestine, due to which their internal area increases. Absorption also increases as the area increases. This absorbed food reaches the blood.

Page no. 105 

Q1. What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?

Ans: Adequate amount of oxygen is found in the atmosphere which is easily taken up by the terrestrial organisms but there is a small amount of oxygen in the water and it is mixed in the water, so the aquatic organisms are able to take this found oxygen at great speed. Breathe and fight

Q2. What are the different ways in which glucose is oxidised to provide energy in various organisms?

Ans: Glucose is oxidised in sufficient amount of oxygen in muscles and provides energy and when there is less amount of oxygen, it gets synthesized and forms lactic acid. Oxidation pathway is following in the cells of organisms.

(i) Aerobic Respiration : In this process Oxygen breaks down glucose into water and CO₂ breaks into Glucose is synthesized in sufficient amount of oxygen to form two molecules of 3 carbon atom pyruvate.

(ii) Anaerobic Respiration: In the absence of oxygen, fermentation takes place in yeast and pyruvate, ethanol andCO₂  are formed.

(iii) Lack of oxygen leads to the formation of lecitic acid, which causes camps in the muscles.

Q3. How is oxygen and carbon dioxide transported in human beings?

Ans: The transport of oxygen and carbon dioxide in humans is called respiration. This process is carried out by the lungs. Hemoglobin (red blood particles) from the air reached through the lungs, takes up oxygen and reaches all the cells of the body. In this way oxygen reaches every part of the body. Similarly, CO2 which is formed in our body when glucose is broken down and converted into energy. This CO2 dissolves in its plasma when it comes in contact with blood. This CO2 is carried from the whole body through the plasma again from the blood to the air and hence is expelled from the nasopharynx.

Q4. How are the lungs designed in human beings to maximise the area for exchange of gases?

Ans: Human lungs are divided into small tubes. Bronchus After the bronchioles, there are alveoli, whose structure is similar to that of a balloon. The alveoli itself facilitates the transport of gases and covers a large area.

Page no. 110

Q1. What are the components of the transport system in human beings? What are the functions of these components?

Ans: The major components of the carriage system in humans are: heart, blood and blood vessels.

(i) Heart : The heart like a pump exchanges blood with different parts of the body.

(ii) Blood : Contains three blood cells. Their liquid medium is plasma. Blood is present in the body.

Carries CO₂, food, water, oxygen, and other materials. RBC cells carry CO₂ and oxygen gases and other substances. WBC makes the body disease free by fighting the bacteria from outside in the body. Platelets prevent blood from flowing through an injury.

Q2. Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?

Ans: Mammals and birds require more energy, which is obtained when glucose is broken down. Oxygen is required for the breakdown of glucose. Only by separating oxygenated and deoxygenated blood can the body provide such a large amount of energy.

Q3. What are the components of the transport system in highly organised plants?

Ans: The major components of the carriage system in highly organized plants are:

  (i) Xylem Tissue

(ii) Phloem tissue

Q4. How are water and minerals transported in plants?

Ans: Xylem tissue carries water and minerals in plants. Root cells are inside the soil and they exchange ions. This creates a difference between the root and the root ion in the soil. To bridge this gap, water moves into the root xylem and forms a column of water, which is continuously pushed upwards. This pressure cannot reach the water upwards. There is a loss of water by the leaves through transpiration, which draws water through the cells present in the roots. Therefore, transpiration traction is the important force for the movement of water.

Q5. How is food transported in plants? 

Ans: Leaves prepare food. Phloem vessels carry food from the leaves throughout the plant.

Page no. 112

Q1. Describe the structure and functioning of nephrons.

Ans:

Q2. What are the methods used by plants to get rid of excretory products?

Ans: Following are the methods to get exemption from Utji product:

(i) Plants produce oxygen in photosynthesis and use carbon dioxide through stomata for respiration.

(II) Plants can reduce the water present in large numbers by the process of transpiration.

(III) Plants excrete some waste material to the soil around them.

Q3. How is the amount of urine produced regulated?

Ans: The amount of urine depends on the water consumed by the human being and the absorption by the body. When drinking less water, the amount of urine is less, some hormones keep it under control. The amount of water also increases for the excretion of urea and uric acid. Hence more urine is excreted.

NCERT Solutions Exercise

---

Q1. The kidneys in human beings are a part of the system for

(a) nutrition.

(b) respiration.

(c) excretion.

(d) transportation.

Answer: (c) excretion.

Q2. The xylem in plants are responsible for

(a) transport of water.

(b) transport of food.

(c) transport of amino acids.

(d) transport of oxygen.

Answer: (a) transport of water.

Q3. The autotrophic mode of nutrition requires

(a) carbon dioxide and water.

(b) chlorophyll.

(c) sunlight.

(d) all of the above.

Answer: (d) all of the above.

Q4. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in

(a) cytoplasm.

(b) mitochondria.

(c) chloroplast.

(d) nucleus.

Answer:(b) mitochondria.

Q5. How are fats digested in our bodies? Where does this process take place?

Answer: Digestion of fat takes place in the small intestine of the alimentary canal. In the stomach, lipase acts on them and breaks down the fat. After this, the bile juice secreted by the liver in the small intestine emulsifies the fat. Pancreatic juice converts this fragmented fat into fatty acids and glycerol, thus the fat gets digested in the small intestine.

Q6. What is the role of saliva in the digestion of food?

Answer: The salivary glands present in the mouth secrete salivary juice. It contains salivary amylase enzyme. which converts starch into maltose sugar. For this reason, when you chew too many times, the food starts to taste sweet.

Q7. What are the necessary conditions for autotrophic nutrition and what are its by products?

Answer: Only green plants on earth are autotrophs which make their own food. For this some conditions are required such as:

(i) Adequate amount of water that the roots absorb.

(ii) sunlight and energy.

(iii) Carbon dioxide gas.

Q8. What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

Answer: Aerobic Respiration:

(i) It occurs in the presence of air.

(ii) Glucose is completely broken down.

(iii) Its end products are: CO₂, water and energy.

(iv) Example: All higher organisms.

anaerobic respiration :

(i) It occurs in the absence of air.

(ii) Glucose is partially broken down.

(iii) Its end products: ethyl alcohol and CO₂.

(iv) Example: yeast, tapeworm.

Q9. How are the alveoli designed to maximise the exchange of gases?

Answer: The alveoli due to their balloon-like shape facilitates the exchange of air and increases the surface area. When filled with air, these alveoli expand and turn into lungs.

Q10. What would be the consequences of a deficiency of haemoglobin in our bodies?

Answer: Hemoglobin carries oxygen in our body. If their quantity decreases in red blood cells, then the organs of the body do not get oxygen smoothly. Due to which the oxidation of food is not completely done, due to which there is also a decrease in energy and tiredness arises. Due to its deficiency, a person suffers from anemia.

Q11. Describe double circulation in human beings. Why is it necessary?

Answer: Blood circulates twice in human heart. Its called double circulation. For this reason, oxygenated and deoxygenated blood remains separate from each other. If this division is not done, then both types of blood will mix and the organs will not be able to get full oxygen.

Q12. What are the differences between the transport of materials in xylem and phloem?

Answer: Carrying of substances by xylem:

(i) In this water and mineral salts flow only in the upward direction.

(ii) Convection of water and salt takes place by pressure and transpiration by traction.

  Carrying of substances by phloem:

(i) In this, the transport of food, amino acids is upward and downward in both the directions.

(ii) ATP energy is used in this.

Q13. Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.

Answer: alveoli

(i) The alveoli carries pure and impure air.

(ii) The size of the alveoli is small.

(iii) The chemical in the alveolar body is released in the form of CO₂  gas.

Renal :

(i) Nephron carries pure and impure blood air.

(ii) The nephrocytes are of large size.

(iii)Nitrogenous chemicals are released in the body in the form of urine.

VERY SHORT-ANSWERS QUESTIONS:

Q1 : The glucose combines with oxygen in our body cells and provides energy. What is the special name of this reaction?

Ans : Cellular Respiration.

Q2 : Name the smallest blood vessels.

Ans: Capillaries. 

Q3: What is the most important characteristic of living organism?

Ans:  Molecular movement.

Q4:  Name the enzyme present in saliva and its function?

Ans: The enzyme is salivary amylase which breaks down starch into sugar.

Q5: Which gland of stomach secretes gastric juice?

Ans: Gastric gland.

Q6:  What are the three constituents of gastric juice and its constituents?

Ans: Hydrochloric acid , pepsin and mucous.

Q7:  Name the energy currency of body.

Ans: ATP ( adenosine try phosphate)   

Q8: Why does trachea have rings of cartilage?

Ans: It ensures that air passage does not collapse.

Q9: What is the function of balloon like structure of lungs?

Ans: Explain mechanism of breathing.

Q10: Name the respiratory pigment of our blood? In which component is it present?

Ans: Haemoglobin. It is present in RBC.

Q11:  Why respiratory pigment is required for transportation?

Ans: Because it has a very high affinity for oxygen.

Q12: What is the average surface of our lungs?

Ans: About 80 square meter.

Q13:  What type of tissue is blood?

Ans: Blood is a connective tissue.

Q14: Name the three substances transported by blood?

Ans:  Salts, Oxygen and Nitrogenous wastes.

Q15:  What is the advantage of separation of oxygenated and deoxygenated blood in 4 chambered heart?

Ans: Such separation allows a highly efficient supply of oxygen to the body. Our heart have to pump two times once for lungs and next for the whole body.

Q16: Name the device that measures blood pressure? What is the normal blood pressure of human beings?

Ans: Sphygmomanometer. 80 mm of Hg – 120 mm of Hg. 

Q17:  Name the blood vessel where arteries and vein join?

Ans: capillaries.

Q18: Name the largest artery of the body.

Ans: Aerota.

Q19:  Write the functions of Platelets.

Ans:  It makes clot to stop bleeding. 

Q 20: what is called the cup shaped structure which collect the urine from each nephron?

Ans: Bowman capsule.

Q 21:  What is Bowman capsule? Write its function.

Ans: Bowman capsule is a cup shaped structure which ends the nephron tube that collects filters urine. 

Q22:  Name the technique which is used in artificial kidney.

Ans:  Dialysis.

SHORT-ANSWERS QUESTIONS:

Q1: Why are viruses in the border of living and nonliving?

Ans: This is fact that viruses are in the border of living and nonliving. The out of body the viruses are nonliving and inside the body these are living. 

Q2. Define life processes?

Ans: Those processes of the body which are necessary to prevent damage and break down and which together perform maintenance job are called life processes. 

Q3. Define photosynthesis?

ANS: Photosynthesis is a process in which green plants make their own food in the presence of sunlight and chlorophyll using carbon dioxide and water to give oxygen and glucose.   

Q4. Name the stored carbohydrate of plants and animals?

ANS:

plants – starch

Animals – glycogen.

Q5 :  Name two enzymes which are secreted by exocrine part of pancreas.

Ans: The pancreas secretes pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.

Q6:What happens to the energy released in respiration process?

ANS: The energy released during cellular respiration is immediately used to synthesis a molecule called ATP which is used to fuel all other activities in the cell.

Q7:  What are the two factors on which diffusion of gases between plants and environment depends?

ANS: There are two factors on which diffusion of gases between plants and environment depends;

(i)  Environment condition and

(ii) The requirements of plants.

Q8:  Write a major difference between function of kidney and artificial kidney.

ANS: The kidney reabsorbs the urine products, but in artificial kidney, there is no re-absorption involved.

Q 9:  Normally, in a healthy adult, the initial filtrate in the kidneys is about 180 L daily. However, the volume actually excreted is only a litre or two a day, Give region.

Ans:  Normally, in a healthy adult, the initial filtrate in the kidneys is about 180 L daily, but the the remaining filtrate is reabsorbed in the kidney tubules.

Q10:  What is Artificial kidney (Hemo- dialysis)? Write its use.

Ans:  An artificial kidney is a device to remove nitrogenous waste products from the blood through dialysis. It used in the patient with kidneys failure.

Q 11:  Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?

ANS: Mammals and birds need high energy. These need only oxygenated bloods. If oxygenated and deoxygenated blood mixed up it cause low in energy. 

LONG – QUESTIONS:

---

Q1: Write events which occur during photosynthesis.

Ans: Events occur during this process –

(i)  Absorption of light energy by chlorophyll.

(ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.

(iii) Reduction of carbon dioxide to carbohydrates.

Q2: What is Villi? Write its two functions.

ANS: Villi are fingers like projection which presence in inner lining of small intestine.

Functions of Villi:

(i) It increases the surface area for absorption.

(ii) Absorption of absorbed food are taken place through villi. 

Q3:  What is bile juice? Write its function. 

ANS: Bile juice is a secretion of liver.

(i) It helps to digest fat from intestine.

(ii) It enhances the activities of enzymes.  

Q4: Name the enzymes which digest the followings.

(i) Protein

(iI) Emulsified fat

ANS:

(i) Trypsin

(ii) Lipase  

Q5:  What is tissue fluid (lymph)? Write its three function.

Ans:  Lymph is tissue fluid, which is similar to the plasma of blood but colourless and contains less protein.

Functions of lymph;

(i) It involves in transportation.

(ii) Lymph carries digested and absorbed fat from intestine.

(iii) It drains excess fluid from extra cellular space back into the blood.

Q6: Name the mode of nutrition;

Ans:

(I) Autotrophic Mode of Nutrition

(ii) Heterotrophic Mode of Nutrition

(a) Saprophytic : food is digested outside the body

(b) Parasitic : nutrition is derived from other organism without killing

(c) Holozoic:  whole material is taken and digested inside body.
Q7. What are the functions of saliva?

ANS: Saliva is secreted by the salivary glands of oral cavity.

(i) It softens food that helps to swallow through esophagus.

(ii) It breaks down the starch into sugar.

(iii) It also helps in digestion.

Q8: Why do herbivores have longer small intestine than carnivores?

ANS: Herbivores have to digest a special kind of carbohydrates cellulose that is found in green

plants. While carnivores needn’t have to digest plants and cellulose. Hence herbivores have

longer small intestine than carnivores.

Q9: What is the secretion of liver and its function.

ANS: The bile juice is the secretion of liver.

Function of bile juice;

(i) Bile salts break down the some fats in the form of large globules into smaller.

(ii) It enhances the enzymes action.

Q10:  Explain the functions of pancreas?

ANS: Pancreas is an organ which secrets pancreatic juice which contains many enzymes like trypsin and lipase and its endocrine part secrets insulin hormone that controls blood sugar label. 

Q11:  What are the end products of carbohydrate, fat, protein digestion?

ANS:

Carbohydrate into glucose,

Protein into amino acid and

Fats into fatty acid and glycerol.

Q12:  Why does muscle cramp take place after vigorous exercise?

ANS: After vigorous exercise, there becomes lack of oxygen in our muscle cells this resulting in the breakdown of pyruvate is taken. Here the pyruvate is converted into lactic acid which caused muscle cramps.

Q13: Why do fish open and close the mouth and operculum during respiration?

Ans: Because fish has to take breathe from dissolved oxygen from water.

Q14: Differentiate between aerobic & anaerobic respiration.(Hint-product, energy, site, oxygen dependence)

Ans:  

aerobic respiration	anaerobic respiration
It occurs in presence of oxygen. It produces high energy. It occurs in mitochondria. Its products are ethanol, CO­2 and energy.	It occurs in absence of oxygen. It produces less energy. It occurs in yeast cell. Its products are CO­2 water and energy

Q15: What are the characteristics of respiratory surface?

Ans: The characteristics of respiratory surface.

(i) It does the process of diffusion./

(ii) Increased  respiratory surface in area increases diffusion.

Q16: Name the organ and their function in transportation?
(i)  Pumping organ.
(ii) Network of tubes.
Ans:

(i)  Pumping organ - Heart

(ii) Network of tubes - xylem and phloem
 

Q17: Differentiate systole and diastole?

ANS:

Systolic Pressure	Diastolic pressure
The pressure of blood inside the artery during ventricular systole is called systolic pressure. It is about 120 mm of Hg.	The pressure of blood inside the artery during ventricular diastole is called diastolic pressure. It is about 80 mm of Hg.

Q18: Write the functions of blood cells.

ANS: Function of blood cells.

1. RBC – It is responsible for transportation of gages and essential nutrients.
2. WBC – it fight against foreign particles and infectious agents.
3. Platelets –(i) It makes clot to stop bleeding.

(ii)    It repairs the injured and leakage blood vessels.

Q19: Differentiate between xylem and phloem.

ANS:

Xylem – (i) The xylem carries water and minerals obtained from the soil.

Phloem – (i) phloem transports products of photosynthesis from the leaves where they are synthesized to other parts of the plant.

Q20: How does water enter into root cells from soil?

Ans:  At the roots, cells in contact with the soil actively take up ions. This creates a difference in the concentration of these ions between the root and the soil. Water, therefore, moves into the root from the soil to eliminate this difference.

Q21: Differentiate blood and lymph?

ANS:

blood	lymph
1.  It contains blood cells water and plasma. 2. It flows into blood vessels like veins, arteries and  capillaries. 3. It carries oxygen and carbon dioxide.	1. It contains plasma water and less protein. 2. It drains into lymphatic capillaries from the intracellular space. 3. It carries digested and absorbed fat from intestine.

Q22: Name the blood vessel that:
(i) Carries blood to lungs.

ANS: pulmonary artery.
(ii) Brings blood to heart from lungs.

ANS: pulmonary vein.
(iii) Carry deoxygenated blood to heart.

ANS: Veins
(iv) Take oxygenated blood to body part.

ANS: artery

Q23: Write the functions of nephrons?

ANS:

(i) It filters the blood in order to remove nitrogenous waste like urea and uric acid.

(ii) It removes Some substances in the initial filtrate, such as glucose, amino acids, salts and a major amount of water, are selectively re-absorbed as the urine flows along the tube.

Q24:  Describe double circulation in human beings. Why is it necessary?

ANS: Our heart pumps two times in each circulation is called double circulation. Once when Rt. Atrium collects blood from body and pushes to Rt. Ventricle to pump for lungs. Lt. Atrium collects oxygenated blood from lungs and pushes to Lt. Ventricle to pump for body. It is necessary so that oxygenated blood cannot be mixed with de-oxygenated.

Q25: Write the role of four chambered heart in our body.

ANS: Our body needs high energy. We get energy from oxygen. Four chambered heart does not allow mixing the oxygenated and de-oxygenated blood during pumping.

Q26: Name the animals having;

1. Two chambered heart.
2. Three chambered heart
3. Four chambered heart

Ans:   (i) Fish (ii) snake and frog (iii) human being

Q27: Draw the structure and write the function of nephron.

ANS: The each kidney is a cluster of very thin-walled blood capillaries. Each capillary cluster in the kidney is associated with the cup-shaped end of a tube that collects the filtered urine. Each kidney has large numbers of these filtration units called nephrons packed close together. It filters the blood in order to remove nitrogenous waste like urea and uric acid.