Students who are planning to build their career stream in the field of medicine can refer to this article as biology plays a major role in the medical field.
In this article, we have covered all the important topics in the exercises and each answer comes with a detailed explanation to help the class 10 students to understand concepts better. Question 1 Ncert Solutions For Class 10th Science Chapter 9 Eng Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
Answer: In multicellular organisms like humans, all the body cells are not in direct contact with the surrounding environment. Therefore, every cell of the body will not get oxygen as per need by the process of diffusion from the environment.
Therefore diffusion is insufficient to meet the oxygen requirements of multicellular organisms. Question 2 What criteria do we use to decide whether something is alive?
Answer: The main criteria used to decide whether something is alive are breathing and respiration. However, living beings also show growth and movement. Question 3 What are outside raw materials used by an organism? Answer: Any organism uses organic molecules as raw material. Heteroptrophs use food and autotrophs use carbon dioxide, minerals, water and all organisms use oxygen for respiration as raw materials.
Question 4 What processes would you consider essential for maintaining life? Answer: Processes essential for maintaining life are : i Nutrition ii Respiration iii Transportation iv Excretion. Question 1 What are the differences between autotrophic nutrition and heterotrophic nutrition? Question 2 Where do plants get each of the raw materials required for photosynthesis? Question 3 What is the role of the acid in our stomach? Answer: Role of acid in our stomach is : i To make acidic medium which is necessary for the activation of the enzyme pepsin.
Question 4 What is the function of digestive enzymes? Answer: The food we eat is complex in nature, i. Digestive enzymes break down these complex molecules into smaller simpler molecules so that they can be absorbed by the walls of the intestine.
Question 5 How is the small intestine designed to absorb digested food? Answer: The small intestine is designed to provide maximum area for absorption of digested food and its transfer into the blood for its circulation into the body. For this the inner lining of the small intestine has numerous finger-like projections called villi. The villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body. Question 1 What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Answer: Aquatic organisms use oxygen dissolved in surrounding water. Since air dissolved in water has fairly low concentration of oxygen, the aquatic organisms have much faster rate of breathing. Terrestrial organisms take oxygen from the oxygen-rich atmosphere through respiratory organs. Hence, they have much less breathing rate than aquatic organisms. Question 2 What are the different ways in which glucose is oxidised to provide energy in various organisms?
Answer: First step of breakdown of glucose 6 carbon molecules takes place in the cytoplasm of cells of all organisms. This process yields a three carbon molecule compound called pyruvate. Further break down of pyruvate takes place in different ways in different organisms. The release of energy in aerobic respiration is much more than in anaerobic respiration.
Formation of lactic acid in muscles causes cramp. Question 3 How is oxygen and carbon dioxide transported in human beings? Answer: i Transport of oxygen : Haemoglobin present in the blood takes up the oxygen from the air in the lungs. It carries the oxygen to tissues which are deficient in oxygen before releasing it. Therefore, it is mostly transported from body tissues in the dissolved form in our blood plasma to lungs.
Here it diffuses from blood to air in the lungs. Question 4 How are the lungs designed in human beings to maximise the area for exchange of gases? Answer: Within the lungs, the air passage divides into smaller and smaller tubes, called bronchi which in turn form bronchioles. The bronchioles terminate in balloon-like structures, called alveoli.
The alveoli present in the lungs provide maximum surface for exchange of gases. The alveoli have vary thin walls and contain an extensive network of blood vessels to facilitate exchange of gases. Question 1 What are the components of the transport system in human beings? What are the functions of these components? Answer: The transport system circulatory system in human beings mainly consists of heart, blood and blood vessels.
It receives purified blood from lungs and pumps it around the body. It also protects the body from diseases and regulates the body temperature. Question 2 Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds? Answer: Separation of oxygenated and deoxygenated blood allows good supply of oxygen to the body. This system is useful in animals that have high energy requirement. Mammals and birds constantly need oxygen to get energy to maintain their body temperature constant.
Question 3 What are the components of the transport system in highly organised plants? Answer: In highly organised plants there are two conducting tissues xylem and phloem.
Xylem consists of vessels, tracheids and other xylem tissues. The interconnected vessels and tracheids form a continuous system of water conducting channels reaching all parts of the plant. Xylem carries water and minerals. Phloem conducts soluble products of photosynthesis from leaves to different parts of the plant body.
Question 4 How are water and minerals transport in plants? The root hair are directly in contact with the film of water in between the soil particles. Water and dissolved minerals get into the root hair by the process of diffusion. The water and minerals absorbed by the root hair from the soil pass from cell to cell by osmosis through the epidermis, root cortex, endodermis and reach the root xylem.
The xylem vessels of the root of the plant are connected to the xylem vessels of its stem. Therefore the water containing dissolved minerals enters the root xylem vessels into stem xylem vessels. The xylem vessels of the stem branch into the leaves of the plants.
So, the water and minerals carried by the xylem vessels in the stem reach the leaves through the branched xylem vessels which enter from the petiole stalk of the leaf into each and every part of the leaf. Thus the water and minerals from the soil reach through the root and stem to the leaves of the plants.
Evaporation of water molecules from the cells of a leaf creates a suction which pulls water from the xylem cells of roots. The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration. Question 5 How is food transported in plants? Answer: The movement of food in phloem or translocation takes place by utilizing energy. The sugar food made in leaves is loaded into the sieve tubes of phloem tissue by using energy from ATR Water now enters the sieve tubes containing sugar by the process of osmosis due to which the pressure in the phloem tissue rises.
This high pressure produced in the phloem tissue moves the food to all parts of the plant having less pressure in their tissues.
This allows the phloem to transport food according to the needs of the plant. Question 1 Describe the structure and functions of nephrons. Answer: Structure of nephron : Each nephron is composed of two parts.
One end of the glomerulus is attached to the renal artery which brings the impure blood containing the urea waste into it. These impurities are filtered. The other part of the nephron is coiled. In this part, the substances like sugar glucose , amino acid, ions and excess water which are required by the body, are reabsorbed. The substance remained in the nephron is mainly urine containing dissolved urea in water which is expelled from the body through urethra from time to time.
The filtrate passes into the tubular part of the nephron. This filtrate contains glucose, amino acids, urea, uric acid, salts and water. Reabsorption : As the filtrate flows along the tubule, useful substances such as glucose, amino acids, salts and water are selectively reabsorbed into the blood by capillaries surrounding the nephron tubule. Urine : The filtrate which remained after reabsorption is called urine.
Urine contains dissolved nitrogenous waste like urea and uric acid, excess salts and water. Urine is collected from nephrons to carry it to the ureter from where it passes into urinary bladder. Question 2 What are the methods used by plants to get rid of excretory products? Answer: i The plants get rid of gaseous products-through stomata in leaves and lenticels in stems. Question 3 How is the amount of urine produced regulated? Answer: The amount of urine is regulated by kidney.
It depends on the quantity of excess water and wastes dissolved in water. When water is less in quantity in the body tissues, a small quantity of concentrate urine is excreted. When there is more quantity of dissolved wastes in the body, more quantity of water is required to excrete them.
Therefore, the amount of urine produced increases. Question 1 The kidneys in human beings are a part of the system for i nutrition ii respiration iii excretion iv transportation Answer: iii Excretion.
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