Class 7 Science Chapter 7 Question Answers - Transportation in Animals and Plants

Short Q & A :

Q1: What do you mean by dialysis? Explain.

Ans :  Dialysis is an artificial process of getting rid of waste and unwanted water from the blood by dialysis machines. Dialysis machines contain a tank with solution of water glucose and salt. Patient’s blood allowed passing through solution for removal of waste. The cleaned blood pumped to vein. The dialysis continues till all blood has been purified.

Q2: Write the two functions of kidneys.

Ans : The two functions of kidney are excretion and osmoregulation. Excretion is the elimination of metabolic waste products from the body. Osmoregulation is regulating osmotic pressure of the body fluids by controlling the amount of water and salts in the body.

Q3: State one function of the following:

1. Arteries
2. Vein
3. Capillaries

Ans : Arteries- carry blood from heart to different parts of body

Veins-carry blood from different parts of body to the heart.

Capillaries-exchange of material between blood and surrounding cells.

Q4: Why is heart known as the pumping organ of the human body?

Ans : Heart is the pumping organs of a human body as it continuously act as a pump for transporting blood to all body parts. Heart pumps carbon-dioxide rich blood to lungs and oxygen rich blood to rest of the body.

Q5: What is the significance of dividing heart into different chambers?

Ans : The division of heart into different chambers ensures that there is no intermixing of oxygenated and deoxygenated blood. This ensures a better efficiency of circulation and transportation of oxygen.

Q6: Explain pulse and pulse rate.

Ans : When blood flows in arteries, it gives throbbing sensation in arteries. This throbbing sensation is known as a pulse. The rate of heart beat or throbbing is known as pulse rate. A person has a pulse rate between 72 to 80 beats per minute. A stethoscope is an instrument used to measure the sound heartbeat.

Q7: Why walls of veins are thinner than the walls of arteries?

Ans : Veins do not have thick walls because blood in vein is no longer under pressure but blood emerges from the heart is under high pressure. So arteries have thick walls.

Q8: How do plants absorb water and minerals from soil?

Ans : Plants absorb water and minerals from soil by the roots. The root hair absorbs water and dissolved mineral nutrients from the soil. The roots remain in contact with underground water.

Q9: Differentiate between arteries and veins.

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Q10: Differentiate between atrium and Ventricle.

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Q11: Why do sponges and hydra not have blood?

Ans :  Animals such as sponges and hydra do not possess any circulatory system. The water in which they live brings food and oxygen as it enter their body the water carries away waste materials and carbon dioxide as it moves out.

Q12: Enlist the functions of blood.

Ans :  

1. It transports substances like digested food from the small intestine to the other parts.
2. It carries oxygen and carbon dioxide to their respective organs and tissues
3. It transports wastes for removal from the body.

Q13: Differentiate between xylem and phloem.

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Q14: Differentiate between RBC and WBC.

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Q15: Why is blood needed by all the parts of the body?

Ans : The blood is needed by all parts of the body because it transports substances like digested food from the small intestine to the other parts of the body. It carries oxygen from the lungs to the cells of the body. It also transports waste for removal from the body.

Q16: Why blood is red in colour?

Ans : The presence of haemoglobin makes blood appear red. Haemoglobin bind with oxygen and transports it to all the parts of the body and ultimately to all the cells. It will be difficult to provide oxygen efficiently to all the cells of the body without haemoglobin.

Q17: What is the function of RBCs?

Ans : Red Blood Cells (RBCs) contain a red pigment called haemoglobin. Haemoglobin bind with oxygen and transports it to all the parts of the body and ultimately to all the cells. It will be difficult to provide oxygen efficiently to all the cells of the body without haemoglobin. The presence of haemoglobin makes blood appear red.

Q18: Does transpiration serve any useful function in the plants? Explain.

Ans : Plants absorb mineral nutrients and water from the soil. Not all the water absorbed is utilised by the plant. The water evaporates through the stomata present on the surface of the leaves by the process of transpiration. The evaporation of water from leaves generates a suction pull which can pull water to great heights in the tall trees. Transpiration also cools the plant.

Q19: Explain stomata and its function in plants.

Ans : Stomata are tiny pores present on the surface of the leaves. These pores are surrounded by ‘guard cells’. Following are its function in plants:

1. The carbon dioxide required in the process of photosynthesis is made available by Stomata, through direct absorption from the air.
2. Stomata help Plants in absorption of mineral nutrients and water from the soil. Not all the water absorbed is utilised by the plant. The water evaporates through the stomata present on the surface of the leaves by the process of transpiration. The evaporation of water from leaves generates a suction pull which can pull water to great heights in the tall trees. Transpiration also cools the plant.

Q20: What will happen if there are no platelets in the blood?

Ans : The platelets are another type of cells in blood, which are responsible for formation of clot in blood when it comes in contact with air. So this prevents excess bleeding from the injury as it plugs the skin opening by clout formation on it. If there are no platelets in the blood, then we may die from a small injury due to excess blooding as there will be no clotting to plug it.

Q21: What is the significance of transport of materials in plants and animals?

Ans : Transport of materials is very important in plant or in animals as all organisms need food, nutrition, water and oxygen for survival. The food is the source of energy and every cell of an organism gets energy by the breakdown of glucose. The cells use this energy to carry out vital activities of life. Therefore food must be made available to every cell of an organism. They need to transport all these to various parts of their body. Further, animals need to transport wastes to parts from where they can be removed.

Q22: Why is it necessary to excrete waste products?

Ans : When our cells perform their functions, certain waste products are released. These waste products are toxic and hence need to be removed from the body. The process of removal of wastes produced in the cells of the living organisms is called excretion.

Q23: What is heartbeat? Name the instrument used to provide information about heartbeat.

Ans : One complete contraction and relaxation of heart makes one heartbeat. Electrocardiogram (ECG) is used to check the rhythm of heartbeat.

Q24: Sometimes doctor inject medicines directly in our bloodstream, where do they inject in artery or in vein?

Ans : Doctor inject medicines in vein because veins are superficial and are easily locatable, secondly medicines need to be transported to all parts of the body through vein medicines reach the heart and from heart it is pumped to all part of body.

Q25: Explain the role of platelets in blood clotting.

Ans : The platelets are responsible for formation of clot in blood when it comes in contact with air. So this prevents excess bleeding from the injury as it plugs the skin opening by clout formation on it. If there are no platelets in the blood, then we may die from a small injury due to excess bleeding as there will be no clotting to plug it.

Long Q & A :

Q1: Describe the function of the heart and circulatory system.

Ans : The heart is a vital organ that continuously beats to act as a pump for transporting blood, which carries essential substances throughout the body.

Key features of the heart include:

• Located in the chest cavity, tilted slightly to the left.
• Approximately the size of a fist.
• Contains four chambers to prevent the mixing of oxygen-rich and carbon dioxide-rich blood:
  • Two upper chambers called the atria (singular: atrium).
  • Two lower chambers called the ventricles.

The circulatory system functions as follows:

• Blood flows from the right side of the heart to the lungs to receive oxygen.
• It then returns to the heart, where it is pumped to the rest of the body.

The walls of the heart's chambers are made of muscle that contract and relax rhythmically, creating a heartbeat.

In summary, the heart and circulatory system work together to:

• Distribute oxygen and nutrients to body cells.
• Remove waste products for excretion.

Q2: Explain the function and components of blood.

Ans : The main components of blood are:

• Plasma: The liquid part of blood.
• Red Blood Cells (RBC): These contain a red pigment called haemoglobin, which binds with oxygen and transports it to all body cells. Without haemoglobin, delivering oxygen efficiently would be challenging. This pigment gives blood its red colour.
• White Blood Cells (WBC): These cells defend the body against infections by fighting germs.
• Platelets: These are responsible for forming clots when blood comes into contact with air. They help prevent excessive bleeding by sealing cuts and injuries.

Blood also plays a crucial role in:

• Transporting nutrients, such as digested food, from the small intestine to other body parts.
• Carrying oxygen from the lungs to body cells.
• Removing waste products from the body.