Question: 1 - Match structures given in Column I with functions given in Column II.
Absorption of water
Transport of food
Transport of water
Transport of water
Absorption of water
Transport of food
Question: 2 - Fill in the blanks.
(i) The blood from the heart is transported to all parts of the body by the ………….
- Arteries begin with the aorta(The aorta is the largest artery in the body. The aorta begins at the top of the left ventricle).
- Arteries carry oxygen-rich blood away from the heart to all of the body's tissues. They branch several times, becoming smaller and smaller as they carry blood further from the heart and into organs.
(ii) Haemoglobin is present in ………….cells.
Answer: Red Blood
RBC contain Haemoglobin
- Haemoglobin is the protein molecule in red blood cells(RBC) that carries oxygen from the lungs to the body's tissues and returns carbon dioxide from the tissues back to the lungs.
- Haemoglobin is made up of four protein molecules (globulin chains) that are connected together.
- RBC is red in colour due to the presence of Hemoglobin.
(iii) Arteries and veins are joined by a network of …………
The human circulatory system consists of a network of arteries, veins, and capillaries, with the heart pumping blood through it.
- Arteries are blood vessels that transport oxygenated blood from the heart to various parts of the body. They are thick, elastic and are divided into a small network of blood vessels called capillaries. The only exception to this is the pulmonary arteries, which carries deoxygenated blood to the lungs.
- Veins are blood vessels that carry deoxygenated blood towards the heart from various parts of the body. They are thin, elastic and are present closer to the surface of the skin. However, pulmonary and umbilical veins are the only veins that carry oxygenated blood in the entire body.
(iv) The rhythmic expansion and contraction of the heart is called…………..
Answer: Cardiac cycle
- The cardiac cycle is the rhythmic contraction and relaxation of the heart.
- Contraction is called cardiac systole and Relaxation is called cardiac diastole. Both contraction and relaxation are together known as the cardiac cycle.
- The heart beats 72 times per minute, i.e., that many cardiac cycles are performed per minute.
- Hence, the rhythmic expansion and contraction of the heart are called Cardiac cycle.
(v) The main excretory product in human beings is ………………
- The major wastes produced by us are:- Carbon dioxide and Urea.
- Carbon dioxide is produced by the process of respiration, and urea is produced by the decomposition of unused proteins in the liver. In humans, the main excretory product is Urea.
- The removal of metabolic waste products from the body of an organism is known as excretion.
- In humans, the major excretory products that are formed during the excretion process is Urea. Hence The main excretory product in human beings is Urea.
(vi) Sweat contains water and …………….
- Sweat glands, also known as sudoriferous or sudoriparous glands, from Latin sudor, meaning ‘sweat’, are small tubular structures of the skin that produce sweat.
- Sweat is mostly water, but it also contains some salts. The body makes sweat to cool itself down.
- When the temperature of the body rises, the body sweats to cool itself.It also has lactic acid, urea, glucose etc. It also has small amounts of sodium chloride which is a salt.
(vii) Kidneys eliminate the waste materials in the liquid form called …………..
- Kidneys are reddish brown, bean-shaped structures situated between the levels of last thoracic and third lumbar vertebra close to the dorsal inner wall of the abdominal cavity.
- The kidneys remove wastes and extra water from the blood to form urine.
- An adult human excretes, on an average, 1 to 1.5 litres of urine per day. The urine formed is a light yellow coloured watery fluid which is slightly acidic (pH-6.0) and has a characteristic odour.
- Healthy kidneys remove extra fluid and waste from your blood, but let proteins and other important nutrients pass through and return to your blood stream
(viii) Water reaches great heights in the trees because of suction pull caused by ………..
- Transpiration is the evaporation of water from the plants.
- The water evaporates through the stomata present on the surface of the leaves.
- Transpiration is mainly responsible for the loss of water that was absorbed by the plants. However, it is important for plants as it helps in the movement of water to the top of tall trees.
- As a result, it helps in the distribution of water throughout the plant body. It also helps in cooling the plant.
- Transpiration pulls in plants consequences of the excretion or evaporation of water that is lost from the surface mesophyll cells present in the leaves
- Transpiration produces a tension or ‘pull’ on the water in the xylem vessels by the leaves.
- Water molecules are cohesive so water is pulled up through the plant.
Question: 3 - Choose the correct options:
(a) In plants, water is transported through
(iv) Root hair
Answer: (i) Xylem
- Xylem moves water from roots to the leaves, and phloem moves food from the leaves to the rest of the plant.
- Xylem transports water and mineral salts from the roots up to other parts of the plant
- The structural elements of xylem are tracheids, vessels or tracheae, xylem fibres, xylem parenchyma and rays.
- The tracheid is derived from a single cell and can be regarded as the basic cell type of xylem tissue.
- Mature xylem vessels:
- contain no cytoplasm
- are impermeable to water
- have tough walls containing a woody material called lignin
(b) Water absorption through roots can be increased by keeping the plants
(i) in the shade
(ii) in dim light
(iii) under the fan
(iv) covered with a polythene bag
Answer: (iii) Under the fan
- Water absorption through the roots can be increased by keeping the plants under the fan.
- As by keeping the plants under the fan, the transpiration process is boosted. Therefore, more amount of water and other minerals are absorbed by the plant roots from the soil.
- The more is the rate of evaporation of water from the plants, the greater is the rate of transpiration.
- Hence, Water absorption through roots can be increased by keeping the plants under the fan.
- So, the correct answer is ‘Under the fan’.
Question: 4 - Why is transport of materials necessary in a plant or in an animal? Explain.
- Transport of materials is necessary for plants or animals because due to it the nutrients and oxygen are made available to all the parts of the body. If the transport of necessary nutrients and oxygen does not take place in the body, the body will not be able to survive.
- The cells of different organs of plants and animals need various necessary substances to carry out many metabolic activities, and different type of waste products are created during these metabolic activities.
- All these materials like food water, oxygen, carbohydrates and hormones etc., are essential for the organisms to survive.
- In plants, materials of transport mainly include gases, water, hormones, minerals, organic material etc. through diffusion, active transport etc.
Question: 5 - What will happen if there are no platelets in the blood?
Answer: Platelets, also known as thrombocytes, perform primarily the function of clotting of bloods. If there are no platelets in the blood, a coagulum or a clot will not form and hence, this will result in unstoppable bleeding leading to severe blood loss and ultimately death of the individual.
The blood clots due to the presence of platelets. If there are no platelets in the blood, then after a minute injury or cut, the blood will not clot and continue to flow outside the body and the person might die.
Activated Platelets forming a Clot
Question: 6 - What are stomata? Give two functions of stomata.
Answer: The numerous pores on the surface of the leaf are called stomata. Transpiration and exchange of gases (carbon dioxide and oxygen) are some of the functions of stomata.
Question: 7 - Does transpiration serve any useful function in plants? Explain.
Answer: During transpiration water evaporates through the stomata present on the surface of the leaves. Transpiration is mainly responsible for the loss of water that was absorbed by the plants. However, it is important for plants as it helps in the movement of water to the top of tall trees. As a result, it helps in the distribution of water throughout the plant. It also helps in the cooling of the plant.
Question: 8 - What are the components of blood?
Answer: The main components of blood are: Plasma, Blood Cells and Platelets.
- Plasma is the liquid component of the blood, a mixture of water, sugar, fat, protein, and salts. The function of plasma is to transport blood cells throughout your body and nutrients, waste products, antibodies, clotting proteins, a chemical messenger.
- Red Blood Cells are the most abundant cell in the blood, accounting for about 40 to 45 per cent of their volume. The shape of a red blood cell is a biconcave disk with a flattened centre – in other words, both faces of the disc have shallow bowl-like indentations (a red blood cell looks like a doughnut).
- White blood cells protect the body from infection. The most common type of white blood cell is the neutrophil. The other major type of white blood cell is a lymphocyte. There are two main populations of these cells. T lymphocytes help regulate the function of other immune cells and directly attack various infected cells and tumours. B lymphocytes make antibodies, which are proteins that specifically target bacteria, viruses, and other foreign materials.
- Platelets help the blood clotting process (or coagulation) by gathering at the site of an injury, sticking to the lining of the injured blood vessel, and forming a platform on which blood coagulation can occur.
Components of Blood
Question: 9 - Why is blood needed by all the parts of a body?
Answer: Blood is a specialized body fluid. It has four main components: plasma, red blood cells, white blood cells, and platelets. About 7 to 8 per cent of your total body weight is blood. An average-sized man has about 12 pints of blood in his body, and an average-sized woman has about nine pints.
Blood is needed by all the parts of the body because:
- It carries oxygen to all the body parts and carries carbon dioxide back to the lungs.
- It carries digested food to various parts of the body for absorption.
- It contains platelets that help in the clotting of blood.
- It helps in maintaining constant body temperature.
- It transports hormones and helps in fighting the body with germs and bacteria.
Question: 10 - What makes the blood look red?
Answer: Blood is red because of the presence of a pigment; called haemoglobin.
Haemoglobin is a protein that forms a complex along with iron molecules and carries oxygen molecules across the body. Iron can reflect red light, and blood looks red because our blood contains so much iron. Thus, haemoglobin makes the blood look red. It is the carrier of oxygen in our body.
Three types of haemoglobin
- Haemoglobin A: This is the most common type of haemoglobin found normally in adults.
- Haemoglobin F (fetal haemoglobin): This type is normally found in fetuses and newborn babies.
- Haemoglobin A2: This is a normal type of haemoglobin found in small amounts in adults.
Question: 11 - Describe the function of the heart.
Answer: The heart is a pumping organ which pumps blood. The heart pumps the deoxygenated blood to the lungs; for oxygenation. Moreover, the heart pumps oxygenated blood to different parts of the body.
Question: 12 - Why is it necessary to excrete waste products?
Answer: Waste products can prove lethal if not removed in time. Hence, it is necessary to excrete the waste products.
- The heart is an organ that pumps blood throughout the body. The human circulatory system is responsible for the transport of materials inside the human body. The organs of the circulatory system are the heart, arteries, veins and capillaries. It comprises four chambers: Atria (upper chambers) Ventricles (lower chambers)
Layers of the heart
- The wall of the heart is made up of three layers:
- Epicardium: This is a protective layer made of connective tissues.
- Myocardium: This layer forms the heart muscles.
- Endocardium: This is the innermost layer and protects the valves and the heart.
Question: 13 - Draw a diagram of the human excretory system and label the various parts
Answer:The human excretory system includes organs that facilitate the removal of nitrogenous wastes from the body. The main excretory organs include kidney, ureter, urinary bladder and urethra. Kidneys filter the blood and urine is the filtrate obtained. Urine passes to the urinary bladder via ureter and is expelled out of the body. This is known as micturition. Kidneys also regulate the osmotic pressure of a mammal’s blood through excessive purification and filtration. This is known as osmoregulation.
The human excretory system organs include:
- A pair of kidneys
- A pair of ureters
- A urinary bladder
- A urethra