Please refer to Life Processes Class 10 Science Important Questions given below. These solved questions for Life Processes have been prepared based on the latest CBSE, NCERT and KVS syllabus and books issued for the current academic year. We have provided important examination questions for Class 10 Science all chapters.
Class 10 Science Life Processes Important Questions
Very Short Answer Type Questions :
Question. What are the raw materials for photosynthesis. How are they obtained by a plant?
Answer : CO2 and water are needed for the photosynthesis. CO2 enters the leaf through stoma present on its surface.
These pores open in day time in most of plants though in desert plants they open at night to reduce the loss of water. Water is absorbed by roots from the soil along with other materials like nitrogen, phosphorus, iron and magnesium.
Question. How do autotrophs obtain CO2 and N2 to make their food?
Answer : CO2 from environment/atmosphere through diffusion/stomata. Nitrogen from soil/environment in inorganic (nitrates) or organic form.
Question. What is the meaning of variegated leaf?
Answer : Variegated leaf means leaf with some green and some non-green part.
Question. Define the term ‘ translocation’.
Answer : Transport of food from leaves to other parts of the plant is called translocation.
Question. Why is respiration considered an exothermic process?
Answer : Respiration is considered an exothermic process due to breaking down of glucose/food in the presence of oxygen with release of energy.
Question. What is breathing?
Answer : The mechanism by which organisms intake oxygen from the environment and release carbon dioxide is called breathing.
Question. Mention two ways in which food gets oxidized in organisms.
Answer : Aerobic respiration and anaerobic respiration.
Question. What role do digestive enzymes play in the alimentary canal?
Digestive enzymes break down complex molecules of food into simpler ones so that they can be absorbed by blood.
Question. Which enzyme is present in human saliva?
Answer : Salivary amylase or ptyalin.
Question. What are the end products of photosynthesis?
Answer : Glucose, oxygen and water.
Question. Give two examples of variegated leaves.
Answer : Crotons, money plant.
Question. How do autotrophs obtain CO2 and N2 to make their food?
Answer: Green plants take carbon dioxide (for carbohydrates) required for photosynthesis directly from atmospheric air and nitrogen (for proteins) in the form of soluble nitrogen compounds present in the soil.
Question. Name the green dot like structures in some cells observed by a student when a leaf peel was viewed under a microscope. What is this green colour due to?
Answer: The green colour of the leaves of the plant is due to the presence of tiny green coloured organelles called chloroplasts which contain green pigment chlorophyll.
Question. Name the intermediate and the end products of glucose breakdown in aerobic respiration.
Answer: The intermediate product of glucose breakdown in aerobic respiration is pyruvate whereas the end products are carbon dioxide and water.
Question. Where does digestion of fats take place in our body?
Answer: Digestion of fats takes place in small intestine.
Question. Name the tissue which transports soluble products of photosynthesis in a plant.
Answer: The phloem is a vascular tissue that transports soluble products of photosynthesis (food or sugar) to all the parts of plants.
Short Answer Type Questions :
Question. (a) Draw a diagram of human alimentary canal and label on it: oesophagus, gall bladder, liver and pancreas.
(b) Explain the statement, ‘bile does not contain any enzyme but it is essential for digestion.’
Answer: (a) The diagram labelled of human alimentary canal is as follows:
(b) Bile is a dark green to yellowish brown fluuid secreted by liver and stored as well as concentrated in the gall bladder. Bile does not contain any digestive enzymes like other secretions from gastrointestinal tract instead has salts which emulsify fats (that are in the form of complicated triglycerol) and breaks it down into small fat droplets that can easily be acted upon by fat digesting enzymes. This is actually a detergent like action of bile. Therefore, bile is essential for digestion though it does not contain any digestive enzyme.
Question. (a) Draw the structure of a nephron and label the following on it: glomerulus, Bowman’s capsule, renal artery, collecting duct.
(b) What happens to glucose that enters the nephron along with filtrate?
Answer: (a) The structure of a nephron is as follows:
(b) Glomerular filltrate present in Bowman’s capsule contains glucose. This filltrate when enters proximal convoluted tubule of kidney then, much of it is reabsorbed back here (65%). Glucose is almost completely reabsorbed in the kidney tubule and is not excreted out.
Question. What is sequence of steps in photosynthesis? How is it different in desert plants and those in temperate regions?
Answer : Chloroplast (chlorophyll), on exposure to light energy, becomes activated by absorbing light energy, and splits water (photolysis of water) to oxygen and hydrogen.
Hydrogen reduces CO2, and synthesizes glucose.
In plants of temperate regions, stomata open during day to take in CO2 and release O2.
Desert plants open stomata at night to check excessive loss of water hence sequence of steps of photosynthesis are slightly different.
These plants take up carbon dioxide at night and prepare an intermediate which is acted upon by the energy absorbed by the chlorophyll during the day.
Question. Design an activity to show that CO2 is produced during breathing.
Answer : Materials Required:
Two test tubes, a cork with two holes, two glass tubes bent at right angle, syringe, lime water Ca(OH)2.
a. Take some freshly prepared lime water, Ca(OH)2 in two test tubes,
b. Fit cork with two holes in test tubes A and B.
c. Fix two glass tubes in this cork of test tube A as shown in the figure.
d. Exhale air into the tube and record your observations.
e. Pass air by the syringe through the lime water contained in test tube B and record your observations. (Image 64)
Lime water turns milky sooner in test tube A than in test tube B.
a. The exhaled air contains lot of CO2 which turns lime water milky.
b. This proves that CO2 gas is exhaled out by humans during respiration.
Question. What is the composition of urine? Are glucose and proteins normally present in urine? Why? How is volume of urine regulated?
Answer : The urine contains mainly water, various salts, urea and uric acid. No, they are not present in urine as glucose is reabsorbed by nephron while protein are not filtered from blood in glomerulus in a healthy kidney.
Volume of urine is regulated by
a. The amount of excess water.
b. The amount of dissolved waste in blood.
Question. a. What is the role of mucus in stomach?
b. What are the two vital functions of human kidney?
Answer : a. To protect the stomach lining from the action of acid and pepsin.
b. The two vital functions of human kidney are:
(i) Excretion – Removal of toxic wastes like urea, uric acid.
(ii) Osmoregulation – The process of maintaining the right amount of water and proper ionic balance in body. It is done by controlling the amount of water and salts reabsorbed by nephron – tubules.
Question. a. How is oxygen and carbon dioxide exchanged between blood and tissue? How are the gases transported in human being?
b. What is haemoglobin?
a. Exchange of gases in tissues occurs through diffusion. Oxygen is carried as oxyhaemoglobin from lungs to tissues. It dissociates and carbon dioxide diffuses out into blood from tissues. It is transported in dissolved form and reaches lungs where again it diffuses to alveoli.
b. Respiratory pigment: Haemoglobin is a red coloured protein present in red blood cells.
Haemoglobin has affinity for O2.
Question. What are the important features of all respiratory structures in animals?
How are alveoli designed to maximize the exchange of gases?
Answer : All respiratory system have some important features.
a. Large surface area.
b. Thin and delicate surface for diffusion and exchange of gases. It is generally located in protected inner part of body.
c. Rich blood supply to respiratory organ. Since all of them are present in alveoli hence it is perfectly
designed for exchange of gases.
Question. What is excretion? Name some parts in our body involved in this life process?
Answer : Excretion means throwing out metabolic waste from living body. Many organs perform this process such as
a. Kidneys remove nitrogenous wastes like urea and uric acid in urine.
b. Sweat and oil by glands in skin.
c. Carbon dioxide and water vapor by lungs.
d. Faces or undigested food by large intestine.
e. Bile pigments by liver. It also converts toxic ammonia to urea.
Question. What is the need to have a transport system in complex organisms?
The transport system of an animal moves substances to where they are needed in the body. Even the smallest animal must have the means of transporting substances around its body. Oxygen and food molecules must move to all the cells, and the waste products must be removed from the cells and expelled into the environment. It occurs through diffusion mainly.
In a multicellular organism, all cells are not in contact with the surrounding hence diffusion will be insufficient for it. A variety of fluid systems, called vascular systems, help such transport in most members of the animal kingdom.
Question. Draw a neat and labelled diagram of human respiratory system. Explain in brief the role of lungs in the exchange of gases.
Answer: The labelled diagram of human respiratory system is as follows:
The primary organs of the respiratory system are lungs, which function to take in oxygen and expel carbon dioxide as we breathe. During the exchange of gases at the respiratory surface (alveoli) of the respiratory organs (lungs) and the oxygen enters the blood and combines with haemoglobin (respiratory pigment) of red blood corpuscles to form oxyhaemoglobin. The oxygenated blood from the lungs is carried to left atrium of heart by pulmonary veins. The heart pumps and distributes the oxygenated blood to the body tissues by arteries where second exchange of gases occurs between blood and body cells. Blood gives oxygen to the body cells and takes carbon dioxide. Inside the cells, oxygen is utilised for oxidation of simple nutrients to produce energy, carbon dioxide and water. Body cells give carbon dioxide to blood and deoxygenated blood is pumped to right atrium of heart from where pulmonary artery carries deoxygenated blood to lungs.
Question. (a) Draw a diagram depicting human alimentary canal and label on it: gall bladder, liver and pancreas.
(b) State the role of liver and pancreas.
(c) Name the organ which performs the following function in human.
(i) Absorption of digested food
(ii) Absorption of water
Answer: (a) Refer to answer 6(a).
(b) Liver is the largest gland of the body that secretes bile juice. Bile juice neutralises acidity of food coming from stomach and provides alkaline medium and helps in digestion of fats in small intestine by bringing about fat emulsification (conversion of large fat droplets into smaller ones) making it easier for enzymes to act and digest them. Pancreas is a soft, lobulated greyish-pink gland which has both endocrine and exocrine parts. Cells of exocrine part secrete pancreatic juice which contains enzymes like pancreatic amylase, trypsin and lipase that help in digestion of starch, proteins and fats, respectively. The cells of endocrine part secrete hormones glucagon and insulin that take part in glucose metabolism.
(c) (i) The absorption of digested food takes place in small intestine.
(ii) Absorption of most of the water from undigested food takes place in large intestine.
Question. (a) Draw a diagram of excretory system in human beings and label on it : aorta, vena cava, urinary bladder and urethra.
(b) List two vital functions of the kidney.
(b) Two vital functions of kidneys are:
(i) The most important function of kidneys is filltration of blood to excrete the waste products of metabolism. If these waste products, mainly nitrogenous waste such as urea and uric acid, are not removed from the blood, they will start accumulating to unbearable toxic levels.
(ii) Osmoregulation : Kidneys maintain water balance in the body and removes excess water.
Besides filltering out the waste products, the kidneys perform other functions such as secretion of erythropoietin, enzyme-renin, homeostasis and conversion of inactive form of vitamin D to the active form.
Question. What will happen to a plant if its xylem is removed?
Answer: Xylem is the main water conducting tissue of plant. If it is removed then water and minerals absorbed by plant roots will not be able to reach different plant parts and plant will wilt and ultimately die.
Question. State the basic difference between the process of respiration and photosynthesis.
Answer: Respiration involves breakdown of food (like glucose) by using oxygen and releasing carbon dioxide, water and energy whereas photosynthesis is synthesis of food (like glucose) by using carbon dioxide, water and sunlight and releasing oxygen. Therefore, respiration is just reverse of photosynthesis.
Question. Write any three differences between aerobic and anaerobic respiration.
Answer: Differences between aerobic and anaerobic respiration are as follows:
Question. Write one function of each of the following components of the transport system in human beings.
(a) Blood vessels (b) Blood platelets
(c) Lymph (d) Heart
Answer: (a) : The blood vessels are tubes that transport blood throughout the body. There are three kinds of blood vessels in human body; arteries, veins and capillaries.
(b) Blood platelets are irregular disc shaped cytoplasmic fragments that assist in formation of blood clot at the site of injury and prevent excessive loss of blood.
(c) Lymph is a mobile connective tissue and acts as ‘middle man’. It takes part in nutritive process as it carries protein molecules from tissue into the blood stream. It also helps in removing waste products like fragments of dead cells, germs, etc.
(d) Human heart is a muscular organ that pumps blood throughout the body via the circulatory system, supplying oxygen and nutrients to the tissues and removing carbon dioxide and other wastes from the same.
Question. Draw a neat and labelled diagram of human excretory system. Describe in brief the function of kidneys, ureters, urinary bladder and urethra.
Answer: The labelled diagram of human excretory system is as follows:
(i) Kidneys : These are main or primary excretory organs present as one pair of large-sized, reddishbrown coloured and bean shaped structure in the upper part of abdomen. The function of kidneys is to remove the poisonous substance, urea, other waste salts and excess water from the blood and excrete them in the form of a yellowish liquid called urine.
(ii) Ureters : These are a pair of long, narrow, thinwalled and tubular structures which conduct the urine from the kidneys to urinary bladder.
(iii) Urinary bladder : It is a thin-walled, elastic, pear-shaped and distensible sac which temporarily stores the urine. Its wall is lined with smooth (involuntary) muscles.
(iv) Urethra : It is a muscular and tubular structure which carries the urine from urinary bladder to the outside.
Question. (a) Draw a sectional view of the human heart and label on it: pulmonary arteries, vena cava, left ventricle.
(b) Why is the double circulation of blood necessary in human beings?
Answer: (a) The sectional view of human heart is as follows:
(b) The blood passes through human heart twice for one supply to the body. One circulation involves the transport of deoxygenated blood from all body parts into the heart. This blood is transported to lungs for oxygenation. The second circulation involves entry of oxygenated blood from lungs into lef side of the heart from where it is distributed to all parts of the body. Double circulation is made possible because the human heart is divided into two halves. One half pumps deoxygenated blood to the lungs and the other half pumps oxygenated blood to the rest of the body.
Double circulation prevent any mixing of oxygenated and deoxygenated blood in the body ensuring maximum supply of oxygen to all body parts. This is necessary for humans who need
a lot of energy to maintain their constant body temperature against any external temperature fluctuations. The rich oxygen supply enables optimum oxidation of glucose in body cells to
release the required energy.
Question. (a) Draw a schematic representation of transport and exchange of oxygen and carbon dioxide during transportation of blood in human beings and label on it:
lung capillaries, pulmonary artery to lungs, aorta to body, pulmonary veins from lungs.
(b) What is the advantage of separate channels in mammals and birds for oxygenated and deoxygenated blood?
Answer: (a) The schematic representation of transport and exchange of oxygen and carbon dioxide is as follows:
(b) In mammals and birds the two circulatory system (oxygenated blood and deoxygenated blood) become fully separate sending low pressure pumping to lungs and high pressure flow of blood to rest of body. This prevents any mixing of oxygenated and deoxygenated blood ensuring maximum supply of oxygen to all body parts. This allows optimum oxidation of glucose to release energy required by these animal groups to maintain their body temperature making them homeothermic.
Long Answer Type Questions :
Question. How are oxygen and carbon dioxide transported in human beings? How are lungs designed to maximise the area for exchange of gases?
Answer: In gaseous exchange, the blood takes up oxygen from the alveolar air and releases CO2 to the alveolar air. Such an exchange occurs because the concentration of O2 is more in alveolar air and O2 moves from higher concentration to lower concentration due to the process of diffusion. The blood has more concentration of CO2 as compared to alveolar air. occus, the CO2 moves from blood to alveolar air due to simple diffusion. This exchange of gases results in the oxygenation of blood.
In times, the exchange of gases occurs between the oxygenated blood and the tissue cells. The concentration of O2 is more in the blood and less in the tissue cells. So, the O2 moves from blood to the tissues and CO2 moves from tissues to the blood. The blood now becomes deoxygenated.
Heart receives this oxygen rich blood from lungs through pulmonary vein and distributes it to all body parts through arteries and collect carbon dioxide rich blood from all body parts through veins and takes it to lungs through pulmonary artery for oxygenation. Deoxygenated carbon dioxide rich air moves out from blood capillaries into the alveoli and is finally breathed out.
Human lungs have a highly branched network of respiratory tubes. A primary bronchus divides into secondary bronchus, which in turn forms tertiary bronchus. Tertiary bronchus divides repeatedly into bronchioles which finally terminate into alveoli. Alveoli are small, rounded polyhedral pouches which are extremely thin-walled and possess a network of capillaries. Exchange of gases takes place in alveoli and hence an alveolus is called a miniature lung.
The alveoli provide a vast surface area where exchange of gases can takes place. Oxygen diffuses from alveoli into pulmonary blood capillaries and CO2 diffuses out from capillaries into alveoli.
Question. Explain the process of digestion of food in mouth, stomach and small intestine in human body.
stomach and small intestine in human body is as follows :
Answer: The process of digestion of food in mouth, stomach and small intestine in human body is as follows :
(i) Mouth : Food is chewed with the help of premolars and molars which increases the rate of action of salivary amylase. Food is mixed with saliva of salivary glands. Salivary amylase
hydrolyses about 30-40% of starch into maltose and isomaltose at pH 6.8.
Starch Salivary amylase → pH 6.8 Maltose + Isomaltose
(ii) Stomach : Food is mixed with gastric juice which contains mucus, hydrochloric acid, pepsin, rennin and a weak lipase enzyme. Mucus lubricates the food and protects the inner lining of the stomach from the action of acid. Hydrochloric acid stops the action of saliva in stomach, kills the bacteria present in the food and provides acidic medium (pH 1-2) of gastric juice so that pepsin gets active for protein digestion.
Pepsin hydrolyses proteins into proteoses and peptones, while gastric lipase enzymes hydrolyses small amounts of fats into fatty acids and glycerol.
Curdling of milk is done by the enzyme rennin, which increases the period of action of pepsin on milk proteins.
Proteins Pepsin→ pH 1-2 Proteoses + Peptones
In addition to chemical digestion, food also undergoes mechanical churning inside the stomach.
(iii) Small intestine : Food is mixed with three digestive juices : bile juice of liver; pancreatic glands. Bile juice neutralises the acidity of the food coming from the stomach and provides alkaline medium and emulsifies (breaks down with the help of bile salts) larger fat globules into smaller fat droplets but is a non-enzymatic digestive juice so has no chemical action on food.
Pancreatic juice contains a number of enzymes like trypsin, pancreatic amylase and pancreatic lipase, which digest the peptones, starch and fats into peptides, maltose, isomaltose and fatty acids respectively.
Fats Lipase → Fatty acids + Glycerol
Intestinal juice also contains number of enzymes like aminopeptidase, intestinal amylase, maltase, isomaltase and lipase enzymes which hydrolyse peptides to amino acids, starch to maltose, maltose to two glucose, isomaltose to two glucose and fats to fatty acids and glycerol.
So, small intestine is the site of the complete digestion of carbohydrates, proteins and fats.
Question. (a) List the three events that occur during the process of photosynthesis. Explain the role of stomata in this process.
(b) Describe an experiment to show that “sunlight is essential for photosynthesis.”
Answer: (a) The three events that occur during the process of photosynthesis are :
(i) Absorption of light energy by chlorophyll : It takes place in grana region of chloroplast. During light reaction, radiant energy of sun is trapped by photosynthetic pigments like chlorophyll and accessory pigments. When exposed to light, chlorophyll molecule is excited and emits electrons.
(ii) Conversion of light energy to chemical energy and splitting of water molecule into hydrogen and oxygen : Emitted electrons from chlorophyll are channeled through electron transport chain in chloroplast. the energy absorbed by chlorophyll is responsible for carrying out three functions:
(i) formation of ATP, (ii) photolysis of water and (iii) synthesis of NADPH (Reduced nicotinamide adenine dinucleotide phosphate).
(iii) Reduction of carbon dioxide to carbohydrate:
Carbon dioxide is reduced to glucose (carbohydrate) by the hydrogen in NADPH and by utilising the chemical energy stored in ATP.
Stomata play an important role in photosynthesis, as gaseous exchange in plants take place through the stomata. Stomata are tiny pores present on the surface of the leaves (also on other green parts like stem). Carbon dioxide required for photosynthesis enters the leaves of the plant through stomata. A large amount of water is also lost through stomatal
pores and oxygen released as by product of photosynthesis goes out through stomatal pores of leaves.
(b) Experiment to show that sunlight is necessary for photosynthesis.
(i) Take a potted plant having green leaves and place it in a completely dark place for about three days to destarch its leaves.
(ii) Take a thin strip of aluminium foil (or black paper) and wrap it in the centre of one leaf on both the sides (while the leaf is still attached to the plant). the aluminium foil should be fixed tightly to the leaf by using paper clips so that sunlight may not enter it from the sides. the aluminium foil should cover only a small part of the leaf so that the remaining part of the leaf remains uncovered and exposed to sunlight.
(iii) Keep this potted plant (with partially covered leaf) in bright sunshine for three to four days.
(iv) Pluck the partially covered leaf from the plant and remove its aluminium foil. Immerse this leaf in boiling water for a few minutes. This will break down the cell membranes of leaf cells and make the leaf more permeable to iodine solution. This leaf is now to be tested for the presence of starch.
But before testing for starch, chlorophyll has to be removed from the leaf.
(v) Now put the leaf in a beaker containing some alcohol. Place the beaker containing alcohol and leaf in a water bath.
(vi) Heat the water in the bigger beaker. then the alcohol in the smaller beaker will also get heated and start boiling soon. This boiling alcohol will extract (or remove) chlorophyll from the green leaf.
(vii) Boil the green leaf in alcohol till all its green pigment ‘chlorophyll’ is removed. The leaf will now become almost colourless or pale (and the alcohol will turn green).
(viii) Remove the colourless leaf from alcohol and wash it thoroughly with hot water to soften it and remove any chlorophyll which may be sticking to it.
(ix) Place the colourless leaf in petri-dish. Drop iodine solution over the decolourised leaf with the help of a dropper. Observe the change in colour of leaf.
(x) The middle part of leaf which was covered with aluminium foil does not turn blue-black on adding iodine solution showing that no starch is present in this middle part of the leaf. This is because sunlight could not reach the covered ‘middle part’ of the leaf due to which the covered ‘middle part’ of leaf could not do photosynthesis to make starch.
(xi) The uncovered part of leaf which was exposed to sunlight turns blue-black on adding iodine solution showing that starch is present in this part of leaf.
(xii) Since the part of leaf which was covered and hidden from sunlight does not contain starch but the part of leaf which was exposed to sunlight contains starch, therefore, we conclude that sunlight is necessary for photosynthesis (to make food like starch).
Question. (a) What are two different ways in which glucose is oxidised to provide energy in various organisms?
(b) Write any two differences between the two ways of oxidation of glucose in organisms.
Answer: (a) Oxidation of food (glucose) within cell may be of two types depending upon the availability of atmospheric oxygen : aerobic respiration and anaerobic respiration.
(i) Aerobic respiration : The oxidative breakdown of respiratory substrates with the help of atmospheric O2 is known as aerobic respiration.
During this process, the respiratory substrate (glucose) is completely broken down into carbon dioxide and water by the process of oxidation and large amount of energy (38 ATP) is produced.
Aerobic respiration includes glycolysis which is common to both aerobic and anaerobic respiration.
The pyruvic acid (pyruvate) molecules formed during glycolysis are carried to the mitochondria where they completely break down to CO2 and H2O with the evolution of a large amount of energy.
Glucose Glycolysis → Cytoplasm Pyruvic acid → Mitochondria CO2 + H2O + Energy
(ii) Anaerobic respiration: Oxidation of respiratory substrates in absence of oxygen is termed as anaerobic respiration. It involves incomplete breakdown of respiratory substrates
in which the end products, such as ethanol or lactic acid are formed and small amount of energy is released. It involves glycolysis, during which glucose is degraded into pyruvate.
Further breakdown of pyruvic acid in absence of oxygen result in the production of ethanol or lactic acid. Anaerobic oxidation of glucose in microorganisms formed ethanol and CO2 and in muscle cells of humans, glucose is anaerobically metabolised into lactic acid.
Question. (a) Draw a sectional view of the human heart and label in it, aorta, right ventricle and pulmonary veins.
(b) State the functions of the following components of transport system.
(i) Blood (ii) Lymph
Answer: (a) The sectional view of human heart is as follows:
(b) (i) Blood is a mobile connective tissue composed of a fluid, plasma and blood corpuscles.
Functions of blood are as follows:
— Blood takes part in transportation of respiratory gases (carbon dioxide and oxygen), nutrients and waste material in the body.
— White blood cells help to fight infection and protect from various pathogenic diseases.
— Lymphocytes of blood produce antibodies and provide immunity against various diseases.
— When an injury is caused, the blood platelets release certain chemicals which help in clotting of blood.
— Blood plasma helps in maintenance of blood pH and uniform distribution of heat in the body.
— Blood carries hormones from endocrine glands to the target organs.
(ii) Lymph is a mobile connective tissue
comprising of lymph plasma (fluid) and lymph corpuscles (cells).
— Lymph acts as ‘middle man’, takes part in nutritive process of body. It transport protein molecules from tissue into blood stream.
— Body cells are kept moist by lymph.
— It absorbs and transports fat and fat soluble vitamins from intestine.
— Lymph drains excess fluid from extra cellular spaces back into blood.
Question. How are water and minerals absorbed and transported in the plants?
Answer : 1. Transpiration is the process of removal of water vapors from the aerial parts of a plant, mainly through stomata in the leaves.
2. There are two conducting tissues of plants: first is xylem and second is phloem. Tracheids and vessels which are two kinds of elements of xylem.
3. Tracheids are found in all vascular plants. They are spindle shaped, have only pits and are not very efficient.
4. Vessels are found in flowering plants, are tube like, have perforation plates and pits making them more efficient.
5. When loss of water in vapour occur from leaves of plants due to transpiration, deficit of water is created in the leaves. Evaporation of water molecules from the cells of a leaf creates a suction force which pulls water from the xylem cells.
6. Water and minerals dissolved in it move up to leaves from root through tracheids and vessels, pulling water and minerals upward through xylem elements-ascent of sap. Thus transpiration helps in upward movement of water from roots to leaves.
7. The roots of a plant absorb water and dissolved substances from the soil, which is needed by the aerial parts of the plants. As such these substances are to be transported from roots up to stem, leaves and flowers.
Question. Describe the mechanism of gaseous exchange in tissues and lungs.
How is oxygen and carbon dioxide transported in human being?
How is oxygen and carbon dioxide transported in human being? Explain clearly how the air is inhaled and exhaled during breathing in humans.
Exchange of gases in tissues:
a. Most of oxygen is carried by haemoglobin in blood. On reaching the tissues, it gets diffused into the cells as it is in higher concentration than in the cells.
b. The carbon dioxide, which is formed in the cells, gets accumulated there in higher concentration as compared in the blood, now diffused into the blood.
c. The CO2 mostly dissolved in blood plasma reaches the lungs, from where it is expelled out during exhalation.
Mechanism of Inhalation:
The thoracic cavity expands when diaphragm and rib muscles contract. The thorax moves upwards and outwards, increasing the volume inside thoracic cavity. The air pressure in the cavity decreases, hence the air rushes into the lungs through nostrils, trachea and bronchi.
Mechanism of Exhalation :
Exchange of gases between alveolar sacs and blood occurs and air having CO2 enters the alveoli. The thoracic cavity comes back to its original size as diaphragm muscles relax. Air containing CO2 is exhaled out through bronchi, trachea and nostrils.
Question. What are the differences between Aerobic and Anaerobic respiration? Name some organisms which use the anaerobic mode of respiration.
Question. a. Mention any two components of blood.
b. Trace the movement of oxygenated blood in the body.
c. Write the function of valves present in between atria and ventricles.
d. Write one structural difference between the composition of artery and veins.
a. plasma, blood cells.
b. Pulmonary vein from lungs ” left atrium left ventricle ” aorta ” arteries to all organs.
c. Valves prevent backflow of blood from ventricles to atria when latter are contracting.
d. Arteries have thick, muscular and elastic walls.
Veins have thinner, less muscular walls but have valves.
Question. a. Define excretion.
b. Name the basic filtration unit present in the kidney.
c. Draw excretory system in human beings and label the following organs of excretory system which perform following functions:
(i) form urine
(ii) is a long tube which collects urine from kidney.
(iii) store urine until it is passed out.
a. Throwing out wastes from the living body.
c. (i) kidney (ii) ureter (iii) urinary bladder
Question. a. What are two vital functions of the human kidney?
b. Draw labelled diagram of human urinary system.
a. The two vital functions of kidney are —
1. Excretion of nitrogenous wastes.
2. Osmoregulation – regulation of water and salt content in blood. (Image 84)
Question. Describe double circulation in human beings. Name the group of animal with double circulation? How is it important for them?
Such a flow in which blood enters the heart twice is called double circulation. It helps in keeping the oxygenated and deoxygenated blood separate.
The right atrium receives blood from the vena cava and pumps the blood into the right ventricle.
Blood is sent to lungs, where it is oxygenated. Then, it is sent through the right and left pulmonary veins to the left atrium where it is pumped to the left ventricle.
The blood then travels to the ascending aorta where it leaves the heart and delivers oxygen to different parts of the body.
Birds and mammals have double circulation because they need to maintain a constant body temperature (warm blooded animals or endotherms).
Question. Where are kidneys located in our body? Show the location of different parts of urinary system in man.
What is the importance of kidneys in our body?
The kidneys (renal glands) like high in the abdominal cavity near and on both sides of the vertebral column.
The right kidney is slightly lower than the left to make room for the liver. Each kidney is bean shaped and the concave portion faces medially. The kidney collects and transports urine from the kidney to ureters.
The kidneys regulate:
a. The volume of blood plasma (blood pressure).
b. The concentration of waste products in the blood (excretion).
c. The concentration of electrolytes such as Na+, K+, HCO3- and other ions (osmoregulation).
d. The pH of plasma.
e. Figure :
Question. What are the different components of blood? Give the function of each of them.
Blood is a liquid connective tissue. It is chiefly formed of two components:
a. Fluid matrix or plasma: It is of pale colour and transports much substance like dissolved carbon dioxide, glucose, amino acids, urea etc.
has mainly water, some proteins like albumin, fibrinogen (blood clotting protein) and many other substances to be transported.
b. Cellular elements which are of three types:
(1) Red blood corpuscles (R.B.C) or erythrocyt.es, which transport O2 and CO2. They are enucleated, disc shaped, full of a red colored protein pigment, hemoglobin.
(2) White blood corpuscles (W.B.C) or leucocytes, which fight disease-causing agent. They are larger, nucleated and are of different types.
(3) Blood platelets or thrombocytes, which help in blood clotting. They are fragments of some larger cell hence do not have nucleus.