Question 1.
Most of the digestion and absorption of the food takes place in the?
Year of Question :(2012 D)

• (a) small intestine
• (b) liver
• (c) stomach
• (d) large intestine. (2020)

Answer:

• (a)small intestine

Question 2.
Mention the raw materials required for photosynthesis?
Year of Question :(Board Term I, 2016)

Answer: Raw materials required for photosynthesis are carbon dioxide (CO2), water, light and chloroplast

Question 3.
State the location and function of gastric glands?
Year of Question :(Board Term I, 2016)

Answer: Gastrifc glands are present in the wall of the stomach. They secrete gastric juices containing mucus, protein digesting enzymes pepsin, rennin and hydrochloric acid (HCl)

Question 4.
Name the glands present in the wall of the stomach that release secretions for digestion of food. Write the three components of secretion that are released by these glands?
Year of Question :(Board Term I, 2016)

Answer: Stomachs muscular wall contains gastric glands. These glands secrete gastric juices which contain dilute hydrochloric acid, mucus and two protein digesting enzymes rennin and pepsin

Question 5.
Complete the following flow chart as per the given instructions?
Year of Question :(Board Term I, 2016)

Answer:

• a - Hydrochloric acid (HCl)
• b - Protein digesting enzyme pepsin
• c - Mucus
• d - HCl makes medium acidic for the activation of an enzyme pepsin
• e - Pepsin acts in acidic medium which breaks down proteins into peptones
• f - Mucus protects the inner lining of stomach from corroding action of HCl

Question 6.?

• (a) State the role played by the following in the process of digestion
• (i) Enzyme trypsin
• (ii) Enzyme lipase-
• (b) List two functions of finger-like projections present in the small intestine. (2020)

Answer:

• (a) (i) Enzyme trypsin : This enzyme is produced by the pancreas in an inactive form called trypsinogen. Trypsin converts remaining proteins into peptones and the peptones into peptides and amino acids
• (ii) Enzyme lipase : It is secreted by pancreas and small intestine. Lipase converts fats into fatty acids and glycerol
• (b) Internally, the wall of the small intestine is provided with long finger-like projections called villi. Two functions of villi are
• (i) The villi greatly increase the absorptive surface area of the inner lining of small intestine
• (ii) The large surface area of small intestine helps in rapid absorption of digested food

Question 7.
Explain the significance of photosynthesis. Writd the balanced chemical equation involved in the process?
Year of Question :(Board Term I, 2016)

Answer: Photosynthesis is important for a number of reasons

• (i) Food : By photosynthesis, green plants synthesise food from simple raw materials like CO2 and H2O. Thus, it sustains life on earth
• (ii) Oxygen : Oxygen released during the process of photosynthesis is needed by animals and humans for respiration. It is also required for respiration of microbes. Oxygen also supports combustion of fuels
• (iii) Fuels : Fossil fuels like coal, oil and natural gas are forms of stored solar energy synthesised millions of years ago through photosynthesis. Balanced chemical equation involved in the process of photosynthesis is given as

Question 8.
Differentiate between autotrophs and hetero- trophs and give one example of each?
Year of Question :(Board Term I, 2017)

Answer: Differences between autotrophs and hetero- trophs are as follows

Question 9.
Explain with the help of neat and well labelled diagrams the different steps involved in nutrition in Amoeba.?
Year of Question :(Board Term I, 2015)

Answer: The mode of nutrition in Amoeba is holozoic. The process of obtaining food by Amoeba is called phagocytosis

• Amoeba ingests food by using its finger-like projections called pseudopodia The food is engulfed with a little surrounding water to form a food vacuole inside the Amoeba
• food is digested inside food vacuole by digestive enzymes
• Food is absorbed directly into the cytoplasm of Amoeba by diffusion
• Food is used to obtain energy and growth of Amoeba
• When considerable amount of undigested food collects inside Amoeba then its cell membrane ruptures at any place to throw out this undigested food
• Diagrammatic representation of different stages in the holozoic nutrition (feeding) of Amoeba is as follows

Question 10.?

• (a) What is peristaltic movement
• (b) Stomata remain closed in desert plants during daytime. How do they do photosynthesis? (Board Term I, 2013)

Answer:

• (a) The relaxation of gut muscles to move the partially digested food downwards throughout the alimentary canal is called peristaltic movement
• (b) In desert plants, stomata open at night and take in carbon dioxide (CO2). Stomata remain closed during daytime to prevent the loss of water by transpiration. They store the CO2 in their cells until the sun comes out so that they can carry on with photosynthesis during the daytime

Question 11.?

• (a) Why is nutrition necessary for the human body
• (b) What causes movement of food inside the alimentary canal
• (c) Why is small intestine in herbivores longer than in carnivores
• (d) What will happen if mucus is not secreted by the gastric glands? (2020)

Answer:

• (a) Human body continuously require energy for their life activities like respiration, circulation, excretion, etc. Energy is required even we are sleeping because a number of biological processes keep on occurring. All these processes require energy and this energy is obtained from nutrition. Nutrition is also needed for growth and repair of human body
• (b) The wall of alimentary tract contains muscles which can contract and expand alternately. The contraction and expansion movement of the walls of foodpipe is called peristaltic movement. The peristaltic movement moves the partially digested food in all the digestive organs throughout the alimentary canal
• (c) Herbivores eat plants which is rich in cellulose. Cellulose takes longer time for complete digestion by the enzymes present in symbiotic bacteria. Therefore, they have longer small intestine. Carnivores, feed on flesh which is easier to digest and do not contain cellulose also. Therefore, they have shorter intestine for digestion of food eaten by them
• (d) Gastric glands secrete HCl, mucus, rennin and pepsin enzymes. Mucus protects the inner lining of stomach from the action of HCl and enzymes. In the absence of mucus, there would be erosion of inner lining of stomach leading to acidity and ulcers

Question 12.?

• (a) State the form in which the following are stored
• (i) Unused carbohydrates in plants.
• (ii) The energy derived from food in humans
• (b) Describe the process of nutrition in Amoeba with the help of diagram. (Board Term I, 2016)

Answer:

• (a) (i) Unused carbohydrates in plants are stored in the form of complex sugar known as starch. They are later broken down into simple sugars (glucose) when energy is needed
• (ii) The assimilated food molecules hold energy in their chemical bonds. Their bond energy is released by oxidation in the cell. This energy is trapped by forming bonds between ADP (adenosine diphosphate) and inorganic phosphate (Pi) to synthesise ATP (Adenosine triphosphate) molecules. These bonds are later broken by enzymatic hydrolysis and the energy released is utilised for cellular processes
• (b) Amoeba is a unicellular animal. Amoeba eats tiny (microscopic) plants and animals which float in water. The mode of nutrition in Amoeba is holozoic. The process of obtaining food by Amoeba is called phagocytosis. When a food particle comes close to Amoeba, it ingests the food particle by forming temporary finger-like projections called pseudopodia around it. The food is engulfed with a little surrounding water to form a food vacuole inside the Amoeba. The food is digested inside food vacuole by digestive enzymes and absorbed directly into the cytoplasm of Amoeba cell by diffusion. A part of absorbed food is used to obtain energy and the remaining part is utilised for growth of Amoeba. When considerable amount of undigested food collects inside Amoeba then its cell membrane ruptures at any place to throw out this undigested food. This process is called egestion

Question 13.
Anaerobic process?
Year of Question :(Board Term I, 2016)

• (a) takes place in yeast during fermentation
• (b) takes place in the presence of oxygen
• (c) produces only energy in the muscles of human beings
• (d) produces ethanol, oxygen and energy. (2020)

Answer:

• (a)takes place in yeast during fermentation

Question 14.
Diffusion is insufficient to meet the oxygen requirement of multicellular organisms like human. State reason?
Year of Question :(Board Term I, 2017)

Answer: Due to higher metabolic rate and the volume of human body is so large that oxygen cannot diffuse into all cells of the body quickly as oxygen will have to travel large distances to reach each and every cell. So diffusion is insufficient to meet the oxygen demand of multicellular organisms

Question 15.
Write two different ways in which glucose is oxidised to provide energy in human body. Write the products formed in each case?
Year of Question :(Board Term I, 2019)

Answer: The two different ways by which glucose is oxidised to provide energy in human body are

• (i) Aerobic respiration : The end products in aerobic respiration are carbon dioxide, water and energy

Question 16.?

• (a) In the process of respiration, state the function of alveoli
• (b) Rate of breathing in aquatic organisms is much faster than that in terrestrial organisms. Give reasons
• (c) Complete the following pathway showing the breakdown of glucose

Answer:

• (a) Functions of alveoli are
• (i) They increase the surface area for exchange of gases
• (ii) The thin walls of alveoli facilitate rapid exchange of oxygen and carbon dioxide between alveolar air and blood
• (b) Aquatic animals like fishes obtain oxygen from water present in the dissolved form through their gills. The amount of dissolved oxygen is quite small as compared to the amount of oxygen in the air. Therefore, to obtain required oxygen from water, aquatic animals have to breathe much faster than the terrestrial organisms

Question 17.
Write three points of difference between breathing and respiration?
Year of Question :(Board Term I, 2016)

Answer: Differences between breathing and respiration are as follows

Question 18.
Draw a flow chart to show the breakdown of glucose by various pathways?
Year of Question :(Board Term I, 2016)

Answer: Breakdown of glucose by various pathways

Question 19.
Write three points of difference between respiration in plants and respiration in animals?
Year of Question :(Board Term I, 2016)

Answer: Differences between respiration in plants and animals are as follows:

Question 20.?

• (a) Why is there a difference in the rate of breathing between aquatic organisms and terrestrial organisms? Explain
• (b) Draw a diagram of human respiratory system and label - pharynx, trachea, lungs, diaphragm and alveolar sac on it. (2020)

Answer:

• (a) Terrestrial organisms inspire atmospheric oxygen, while aquatic organisms thrive on the dissolved oxygen present in water. Air contains about 21% of oxygen while water has less than 1% oxygen in dissolved state. Oxygen diffuses through water at a much slower rate as compared to air. A terrestrial organism has the advantage of utilising greater amount of oxygen at a faster rate with lesser effort whereas, aquatic organisms have to put more effort to obtain the same amount of oxygen, therefore breathing in aquatic organisms is much faster than the terrestrial organisms
• (c)The labelled diagram of human respiratory system is a follows

Question 21.?

• (a) State reasons for the following
• (i) Herbivores need a longer small intestine while carnivores have shorter small intestine
• (ii) The lungs are designed in human beings to maximise the area for exchange of gases
• (b) The rate of breathing in aquatic organismsis much faster than that seen in terrestrial organisms. (Board Term 1,2016)

Answer:

• (a) (i) Herbivores need a longer small intestine than that of carnivores because their diet is mostly grass and plants, that contains more fibres and cellulose which are hard to digest. Longer small intestine also hosts many small bacteria that process and break down cellulose into glucose which is a source of energy. Carnivores diet is not rich in cellulose so, they do not need to harbour bacteria for cellulose digestion
• (ii) 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, for the exchange of gases. Due to vast surface area of alveoli, exchange of gases becomes a fast and effective process. Oxygen diffuses from alveoli into pulmonary blood capillaries and CO2 diffuses out from capillaries into alveoli

Question 22.
Draw a flow chart showing the three different pathways involved in the breakdown of glucose in different organisms. Name the respiratory pigment present in human beings. State the function of rings of cartilage present in our throat. (Board Term I, 2015)?

Answer: Respiratory pigment present in human beings is haemoglobin. Rings of cartilage are C in shape, stacked one on top of the other. These cartilaginous rings prevent the trachea from collapsing and blocking the airway

Question 23.?

• (a) Draw a diagram of human respiratory system and label: Trachea, Bronchi and Diaphragm.
• (b) Give reasons for the following:
• (i) Lungs always contain residual volume.
• (ii) Nostrils are lined with mucus. (Board Term I, 2013)

Answer:

• (a)Terrestrial organisms inspire atmospheric oxygen, while aquatic organisms thrive on the dissolved oxygen present in water. Air contains about 21% of oxygen while water has less than 1% oxygen in dissolved state. Oxygen diffuses through water at a much slower rate as compared to air. A terrestrial organism has the advantage of utilising greater amount of oxygen at a faster rate with lesser effort whereas, aquatic organisms have to put more effort to obtain the same amount of oxygen, therefore breathing in aquatic organisms is much faster than the terrestrial organisms
• (b) (i) Lungs always contain residual volume so that during the breathing cycle, when air is inhaled and exhaled, there must be sufficient time for oxygen to be absorbed and for the carbon dioxide to be released. It is also important as it prevents the lungs from collapsing.
• (ii) Mucus and hair present in nostrils help in filtration of inhaled air. It traps harmful substances and germs present in air

Question 24.
Which one of the following statements is correct about the human circulatory system?
Year of Question :(Board Term I, 2016)

• (a) Blood transports only oxygen and not carbon dioxide
• (b) Human heart has five chambers.
• (c) Valves ensure that the blood does not flow backwards.
• (d) Both oxygen - rich and oxygen - deficient blood gets mixed in the heart. (2020)

Answer:

• (c)Valves ensure that the blood does not flow backwards.

Question 25.
Name the vein which brings blood to left atrium from lungs?
Year of Question :(Board Term I, 2013)

Answer: Pulmonary vein carries oxygenated blood from lungs to left atrium of heart

Question 26.
Define translocation in reference to plants?
Year of Question :(Board Term I, 2016)

Answer: The transport of food prepared in the leaves, by the process of photosynthesis, to various parts (roots, stem, branches, etc.) of the plant is called translocation

Question 27.
Write three types of blood vessels. Give one important feature of each?
Year of Question :(Board Term I, 2019)

Answer:

The three types of blood vessels in human body are: (i) arteries, (ii) veins and (iii) capillaries.
• (i) Arteries are the blood vessels which carry blood from heart to various parts of the body. The walls of arteries are thick, elastic and muscular that enables them to dilate but not rupture when the heart contracts and forces blood into them
• (ii) Veins are thin walled blood vessels which bring blood from the body back to the heart. They are larger and hold more blood than the arteries. The lumen of veins are provided with valves to prevent the backflow of blood
• (iii) Capillaries are thin walled and extremely narrow blood vessels which occur at the terminals of artery and vein. The wall of capillaries are permeable to water and dissolved substances so that the exchange of materials between the blood and body cells can take place

Question 28.?

• (a) Write two water conducting tissues present in plants. How does water enter continuously into the root xylem
• (b) Explain why plants have low energy needs as compared to animals. (AI 2019)

Answer:

• (a) Xylem tracheids and vessels are two water conducting tissues present in plants that help in rapid movement of water. In xylem tissue, vessels and tracheids of the roots, stems and leaves are interconnected to form a continuous system of water conducting channels reaching all parts of the plant
• Minerals and water needed by the plants are absorbed by root hairs from the soil by the process of osmosis and take in minerals by the process of diffusion. Thus, a difference in concentration of ions is created between the roots and the soil which enables the water to enter into roots to compensate the difference in concentration. The water, alongwith dissolved minerals from root hairs, passes into xylem vessels through cells of the cortex, endodermis and pericycle and then ascent of sap (i.e., upward movement of water and mineral salts from roots to the aerial parts of the plant against the gravitational force) takes place from xylem of the roots to the xylem of stem and leaves through vessels and tracheids. Evaporation of water molecules from the cells of leaves creates a suction pressure which pulls the water from xylem cells
(a)
• Plants are autotrophic and do not have to move from one place to another in search of their food. Movements in a plant are usually at the cellular level and hence they required less amount of energy. Whereas animals are heterotrophic and locomote in search of food and other activities, hence require higher amount of energy than of plants

Question 29.
Explain how the translocation of materials in phloem tissue in plants is achieved by utilising energy. ?
Year of Question :(Board Term I, 2017)

Answer:: The phloem cells transport the soluble food materials to all parts of plant. The transport of food from leaves to different parts of plant is termed as translocation. Components of phloem are sieve tubes, companion cells, phloem parenchyma and phloem fibres. The food is manufactured in the mesophyll cells (or photosynthetic cells) of a leaf. The manufactured food enters into sieve tubes of the phloem and is transported as a dilute aqueous solution either in upward or downward direction. Food is transported to all non-green parts of the plant for their growth and metabolic activities. Besides food molecules, phloem also transports amino acids, hormones synthesised in the shoot tips and root tips and other metabolites. In this process, glucose is transferred to phloem tissue using energy from ATP. This increases the osmotic pressure of the tissue causing the water to move into it (endosmosis). Soluble material is then transferred from phloem tissue to other tissues which have less pressure than in the phloem. Thus, according to plants requirement, the material is translocated from higher osmotic pressure areas to lower osmotic pressure areas

Question 30.
What do the following transport?
Year of Question :(Board Term I, 2016)

• (i) Xylem
• (ii) Phloem
• (iii) Pulmonary vein
• (iv) Vena cava
• (v) Pulmonary artery
• (vi) Aorta (Board Term I, 2014)

Answer:

• (i) Xylem is a specialised plant conducting tissue that transports water and minerals from roots to all aerial parts of plants which occurs against gravitational force with the help of ascent of sap
• (ii) Phloem transports food that is prepared in the leaves, through photosynthesis, to various parts of plant. This process is called translocation. Phloem also transports amino acids, hormones synthesised in the shoot tips and root tips and other metabolites
• (iii) Pulmonary vein present in human circulatory system brings oxygenated blood from lungs to the left atrium of heart
• (iv) Vena cava transport deoxygenated blood collected by all veins of body except pulmonary vein and pass it to the right atrium of heart
• (v) Pulmonary artery transports deoxygenated blood from right atrium of heart to lungs for oxygenation
• (vi) Aorta transports oxygenated blood from left atrium to systemic arteries which further take the blood to various body parts and organs

Question 31.
Explain giving any three reasons the significance of transpiration in plants?
Year of Question :(Board Term I, 2016)

Answer: Significance of transpiration in plants

• (i) The absorbed water is transported from roots to leaves through xylem vessels which is greatly influenced by transpiration pull
• (ii) The water stream moving upwards carries dissolved minerals with it. Transpiration also helps in distributing these minerals throughout the plant
• (iii) The evaporation of water during transpiration provide cooling effect to the leaves

Question 32. List in tabular form three differences between arteries and veins.?
Year of Question :(Board Term I, 2013)

Answer: Differences between arteries and veins are as follows

• CBSE Class 10
  SA-1
  Science
  Set 1 QP