Class-8 General Science Notes (Gaba Books)- Unit-2 Sustenance of the Individuals (Transport)- SLO-Based Short and Brief Questions and Answers

Unit-2 TRANSPORT OF MATERIALS

SLO-based Short and Brief Questions and Answers within the Book.

Q1. Why must all living organisms transport materials from one part of the body to another? Explain with an example:  

OR

Discuss the importance of the transport of various materials in a living organism.

Ans:

All living organisms must transport materials from one part of the body to another to sustain life. For example:

1. Food and oxygen are transported to all cells in the body for respiration and growth. 

2. Cells transport waste products to the organs responsible for their excretion.

Q2. Write the name of the method used for materials transport in unicellular organisms?

Or

How are nutrients transported in unicellular organisms?

Ans: 

In unicellular organisms like Amoeba, Paramecium, and bacteria, nutrients are transported to every part of the cell through diffusion.

Q3. How are Nutrients transported in aquatic multicellular organisms?

Ans: 

In basic aquatic multicellular organisms like Hydra and jellyfish, oxygen and nutrients are transported by water circulation through their bodies. 

Q4. How are oxygen and nutrients transported in mammals?

Ans: 

In mammals, oxygen and nutrients are transported by the blood that circulates through their bodies i.e. blood is the medium of transport. 

Q5. How are nutrients transported in plants?

Ans: 

In plants, the transport of water and food takes place with the help of specialized tissues called xylem and phloem. These tissues are also called conductive tissues. They are found throughout the plant body.

Q6. Discuss the various methods by which materials are transported in plants and animals. (Long)

Ans.

There are various methods by which materials are transported in plants and animals.

Transport in animals:

• Transport of nutrients in unicellular organisms:

The transport of nutrients in unicellular organisms, such as Amoeba, Paramecium, bacteria, etc. is very simple. The nutrients reach every part of the cell by diffusion. 

• Transport of nutrients in aquatic multicellular organisms:

In simple aquatic multicellular organisms, such as Hydra and jellyfish, oxygen and nutrients are transported by water that circulates through their bodies. 

• Transport of nutrients in mammals:

In mammals, oxygen and nutrients are transported by blood that circulates through their bodies i.e. blood is the medium of transport. 

Transport in plants:

In plants, transport of water and food takes place with the help of specialized tissues called xylem and phloem. These tissues are also called conductive tissues. They are found throughout the plant body.

Q7. Define meristematic tissues?

Ans. Meristematic tissue is made up of a group of cells that divide continuously to form new cells.

Q8.  Discuss the internal structure of the root.

OR

Describe different parts of the root.

The different parts/layers of the root are:

The piliferous layer

It is the outermost layer of the cell bearing root hair. A cuticle is absent in the piliferous layer.

Functions: Helps in the absorption of water and mineral salts

from the soil.

The cortex:

This is a wide region consisting of parenchymatous cells with intercellular air spaces.

Function: It is a food storage tissue.

Vascular Tissue:

Vascular tissue is the main transport systems of plants. It transports water, minerals, and food throughout the plant.  It is comprised of the xylem and the phloem. In a dicot root, the xylem and phloem are not grouped together to form vascular bundles. The xylem and phloem are separated by parenchyma tissue. The xylem tissue conducts water and other substances absorbed from the soil and the phloem tissue conducts food. 

The Pith:

The pith occupies only a small area in the cortex. It is made up of parenchymatous tissues and serves to store food.

Q9.  Write the names of different regions of the dicot stem.

OR

Write the name of the different parts of the dicot stem.

Ans.

There are four main regions in a dicotyledonous stem.

1. Epidermis
2. Vascular bundle
3. Cortex
4. Pith

Q10.  Differentiate between the arrangement of xylem and phloem tissues in Dicot Stem and Root.

Ans. 

👉In a dicot stem, the xylem and phloem are grouped together to form vascular bundles. The vascular bundles are arranged in a ring. In each vascular bundle the phloem lies outside the xylem with a tissue called cambium between them.

👉In a dicot root, the xylem and phloem are not grouped together to form vascular bundles. The xylem and phloem are separated by parenchyma tissue. 

Q11. In what ways xylem and phloem are important in transport for plants?

or

Differentiate between the function of xylem and phloem.

Ans.

Xylem and phloem combinedly called Vascular tissue is the main transport systems of plants. It transports water, minerals, and food throughout the plant. 

➢ Xylem carries water and minerals from the roots to the leaves.

➢ Phloem carries the food prepared by the leaves to different parts of the plant

Q.12  Define Parenchymatous tissues.

or

What are Parenchymatous tissues?

Ans. Parenchymatous tissues are basic tissues of plants consisting of cells with cell wall. These cells remain alive at maturity.

Q13.  Briefly discus the internal structure of a leaf.

OR

Describe the different parts of a leaf.

Ans. Internal Structure of a Leaf:

There are three groups of tissues in a leaf.

1. The epidermis 
2. The mesophyll
3. The vascular tissue

1. The epidermis: 

The epidermis is the outermost layer. It is composed of a single layer of cells which cover the entire leaf surface. A leaf has an upper and lower epidermis on its upper and lower surfaces respectively. The outer surface of the epidermal cells is covered by cuticle. Some of the epidermal cells are modified into stomata, which are more abundant on the lower surface of the leaves.

The mesophyll

It is the main region between the two epidermal layers. It is divided into two regions. 

1. The pallisade mesophyll

The pallisade mesophyll consists of 2-3 layers of cylindrical cells. These cells contain many chloroplasts. Small intercellular spaces are present among them.

2. The spongy mesophyll

The spongy mesophyll consists of loosely arranged irregular cells with large intercellular spaces among them facilitating the diffusion of gases. The cells of this layer also contain chloroplasts.

The vascular tissue:

The vascular bundles are present in the midrib and branch veins in the leaf. Each vascular bundle is made up of xylem, which occurs towards the upper epidermis, and phloem which occurs towards the lower epidermis.

Q14. What are the means of transport of substances in the bodies of living organisms? Discuss briefly.

Ans. Following are the methods which bring about the transport of substances in the bodies of living organisms.

Diffusion:

The molecular movement in gases or liquids which tends to result in their uniform distribution is called diffusion. In diffusion the molecules of a solute move from a solution where there is a higher concentration of its molecules to a solution where their concentration is low. The process of diffusion continues until the concentration of solute in all portions of the solution becomes equal (uniform). Diffusion involves the movement of molecules of gases, solutes and liquids other than water. 

Osmosis:

Osmosis is a special case of diffusion where the movement of a solver usually water, from a region of higher concentration to a region of lower concentration through a semi-permeable membrane.

Q15. Perform an experiment to show the process of Osmosis through a semi-permeable membrane.

Apparatus: 

semi-permeable membrane, sugar solution, thistle funnel, beaker, iron stand.

Procedure: 

A piece of semi-permeable membrane is stretched round a thistle funnel. The prepared funnel is filled with saturated sugar solution and turned upside down in a beaker of distilled water and clamped to an iron stand. The level of sugar solution in the funnel is marked and the setup is left to stand for a few hours.

Result:

A few hours later, the level inside the funnel will be seen to have risen. This has been caused by the movement of water though the membrane into the funnel. No sugar passed out from the thistle funnel, and this can be verified by tasting the distilled water.

Diagram:

Q16. Discuss the process of Osmosis and the material transport in plants. 

Ans. 

The surface membranes of plant and animal cells have selectively permeable properties. When these organisms or their individual cells are surrounded by fluids weaker or stronger than their own, osmotic forces are set up. Water moves from cell to cell in plants by osmosis. The cell membrane of a plant cell is semi-permeable. So, if a cell containing a weak solution is next to a cell with a stronger solution containing more solute, water moves by osmosis from the weak to the strong solution. This process is used by root hair cells in the absorption of water from soil.

Q17. What types of molecules can pass through a semi-permeable membrane. Give examples of semi-permeable membrane.

Ans:

A semi-permeable membrane only allows smaller molecules to pass through it. Examples of semi-permeable membranes include cell membrane, egg membrane, membrane of glomerulus in nephrons of kidneys etc.

Q18. Describe briefly the process of water absorption and transport in plants.

Ans:

The root hairs are delicate hair-like projections of the cells of the outer layer of a root. Root hairs are the absorptive organs of the plant). The film of water which surrounds the soil particles also surrounds the root hairs Soil water, with mineral salts dissolved in it, makes a very weak solution, and the cell sap of the root hair is stronger than it. Water, thus, moves from soil to root hair cells through osmosis, and this process occurs from cell to cell till it reaches the xylem vessels that carry it further upwards. With the help of this process, plant get their supply of water and mineral nutrients.

Q19. Explain the process of transpiration and Water movement.

Ans. 

The process by which plants lose water as water vapours into the atmosphere is called transpiration. 

Plants use only a small amount of the water they absorb from the soil. The rest of the water escapes in the form of water vapours through the stomata. The opening and closing of stomatal apertures regulate the loss of water vapour from the leaves. Most of this loss takes place through the leaves but evaporation also occurs from stems, fruits, and flowers. The evaporation of water from the leaf surface also produces a pulling force which causes the water to move upwards. Transpiration also exerts a cooling effect on plants.

Q20. Describe briefly the process of transportation of food in plants. 

or

Describe the process if translocation.

Ans:

The food prepared by the leaves is transported to all parts of the plant in the form of a solution through a process known as translocation. Translocation takes place mainly from leaf cell to different parts of plant through phloem tissues. However, in some plants, substances made in the roots are also transported to the leaves through the phloem tissue. 

Q21. How are material (oxygen and nutrients) transported in humans? 

or

Describe the transportation process in human beings. 

Ans:

The process of diffusion is too slow to work in higher animals. In such animals, including humans, a well-developed pick-up and delivery system, known as the circulatory system, is present. Thus, transport in humans is carried out by the circulatory system.

Circulatory System:

In the circulatory system, the blood delivers food and oxygen to every cell in the body. It also carries wastes away from every cell in the body.). The circulatory system consists of:

• The heart
• Blood vessels
• Blood.

THE HEART: 

The heart is a muscular organ that beats 60 to 80 times in a minute throughout your life. Its function is to pump blood to all parts of the body.

Heart is divided into two parts or chambers.

Atria: It is top chambers with comparatively thinner walls.

Ventricles: It comprises of two lower chambers with thick muscular walls. 

The right side of the heart, i.e. the right atrium and ventricle, receives blood with carbon dioxide (deoxygenated blood) from all parts of the body to be sent to the lungs. Its left side, i.e. the left auricle and ventricle, receives oxygen-rich blood (oxygenated blood) from the lungs and sends it to all parts of the body. The left auricle receives oxygenated blood as it comes back to the heart from the lungs. The right atrium receives deoxygenated blood from the rest of the body. The right ventricle pumps the blood to the lungs. The left ventricle pumps the blood to the rest of the body. The heart has several valves that allow the blood to flow in one direction only. 

Q22. Describe the complete working of a blood circulatory system.

or

How does blood flow in the blood vessels? 

Ans. 

With each heartbeat, blood is pumped into blood vessels called arteries. Arteries carry blood away from the heart. Arteries further branch into smaller and smaller arteries, and finally into capillaries. Capillaries are the thinnest blood vessels, about as thick as hair. They have very thin walls. It is through these thin capillary walls that:

• Oxygen is picked up from the alveoli in the lungs.
• digested food is picked up in the small intestine.
• The oxygen and digested food are passed on to each cell of the body.
• Carbon dioxide and other wastes are picked up from every cell.
• Carbon dioxide is passed into the alveoli and wastes are passed into the kidneys. 

After passing through the capillaries and picking up carbon dioxide, the blood flows into blood vessels called veins. Veins carry the blood back to the heart. The blood enters the right side of the heart and is pumped to the lungs where it gives up carbon dioxide and picks up oxygen This oxygen-rich blood travels back to the left side of the heart. It is again sent to all other parts of the body and the process is repeated again and again. This process outlines the workings of the circulatory system.

Q23. What is blood? How much blood a normal human has?

Ans. Blood is a liquid tissue. The human body contains 3-5 litres of blood consisting of a fluid known as plasma in which three types of blood cells float.

Q24. What is Plasma called in blood?

Ans.

Plasma is the liquid part of the blood. It is yellowish in colour and contains about 90 percent water. It has food, wastes, enzymes, etc. dissolved in it. It also contains protein that helps the blood to clot.

Q25. How can you feel that your own blood is rushing through the arteries?

or

How can you feel your own pulse.

Ans. 

To feel the blood rushing through my arteries, I will place my two fingers in the hollow spot on the wrist. The throbbing sensation or pulse that I feel is actually my blood rushing through the arteries.

Q26. How many types of blood cells are? explain briefly.

Ans.

There are three types of blood cells:

Red blood cells (RBCs): These are disc-shaped cells. They contain a red-coloured protein called haemoglobin. It is this pigment that absorbs oxygen and transports it to the cells all over the body.

White blood cells (WBCs) These are slightly larger than red blood cells. They are few in number than red blood cells. Their main job is to fight against diseases b killing harmful bacteria and other foreign material. They are able to move on their own like Amoeba. This helps them to pass through the walls of blood vessel and to reach infected parts of the body.

Platelets; These are smaller than red blood cells. They help the blood to clot whenever the is a wound on the body. This blocks the flow of blood and prevents blood loss.

Q27. Write some functions of a blood.

Ans. 

Functions of Blood:

• It carries oxygen to various parts of the body.
• It carries digested food materials to various parts of the body for distribution.
• It transports hormones and a number of other substances.
• It helps in preventing excessive bleeding by forming blood clot.
• It helps in maintaining a constant body temperature.
• it protects the body against invading germs.
• It transports waste materials to the excretory organs for excretion.

Q28. What is a blood transfusion? when it became necessary?

Ans.  

A blood loss of 40 per cent or more in badly injuries can cause death. The doctor must give the patient blood donated by another person (called a donor) to make up for the blood loss. This procedure is called blood transfusion. 

Q29. How many kinds of blood are?

Ans. 

There are four kinds of blood groups known as A, B, AB and O. 

Q30. What precautions are necessary before carrying out a blood transfusion? and why? What will happen when an unmatched group blood transfuse.

Ans. 

Different persons have different blood groups. The Blood of one group does not match with others. Doctors have to be careful to match the blood of the patient with that of the donor before carrying out a blood transfusion. This is because if the blood of unmatched groups gets mixed, the red blood cells stick together, and it can lead to death.

Q31. What is metabolism?

Ans.

During life activities such as cellular respiration, several chemical reactions that take place in the body are known as metabolism.

Q32. Describe briefly the excretory system.

Ans. 

During the metabolism waste products, such as carbon dioxide, water, salts, urea, and uric acid. A build-up of these wastes is harmful to the body. The excretory organs remove these wastes. This process of removal of metabolic wastes from the body is known as excretion.

Q33. How does Excretion take place in animals?

Ans. 

In smaller animals such as Amoeba, Paramecium, Hydra and sponges, there are no special excretory organs and waste products such as ammonia are excreted by the process of diffusion through the body surface.

In larger animals have special organs for excretion-such as tubular structures called nephridia in earthworms and leeches, Malpighian tubules in insects and kidneys in vertebrates.

Q34. Name the organs that carried out excretion in humans

Excretion in humans is carried out by the lungs, skin and the urinary system.

Q35. How does excretion take place in humans by different organs?

1. By Lungs:

The alveoli in the lungs collect carbon dioxide from the blood, which is given out when you exhale. The lungs also give out some excess water in the form of water vapours. 

2. The Skin:

The skin is richly supplied with blood vessels. As the blood flows in capillaries near the skin, water, salts and other wastes diffuse out from the blood into the sweat glands. These wastes then leave the body as sweat through tiny pores in the skin. 

3. The urinary system:

The urinary system is responsible for removing most of the wastes from the body in the form of urine. Urine consists of 95% water, 2.5% urea and 2.5% other waste products. The main organs of this system are the kidneys. 

Q35. Where are kidneys located? and write their functions briefly.

Ans. Kidneys are located on each side of the backbone, just above the waist.

Function of kidneys:

The main function of the kidney is to filter wastes from the blood just like a filter paper to separate solid impurities from a solution. The kidneys work in the same way.

The kidneys consist of a large number of coiled tubes called nephrons.

The wastes collected in the kidneys form a liquid called urine. It passes from the kidneys through two tubes called ureters into an elastic sac called the urinary bladder. The bladder stores the urine until it is excreted from the body through the urethra. A human being passes out about 1.5 to 2.5 litres of urine every day. The kidneys must function properly to keep the body healthy.

Q36. How does excretion in plants

Ans. 

Plants also produce excretory materials in their cells though these are produced may more slowly than in animals. They have no excretory organs to expel them out. The different methods of excretion in plants are as follows:

• The waste gases-carbon dioxide, oxygen, and water vapours, produced during respiration and photosynthesis, are expelled through the stomata of leaves and lenticels of the stem.
• Other waste products are converted into insoluble compounds which remain in the cells. When dead leaves, bark or any other parts fall off a tree, the waste products they contain are also removed. Some plants release waste products from their stems, these wastes including resin, gum, and latex.

Q37. Are all plant wastes useful? 

or

Name some of the useful plant wastes.

Ans. 

Several plant wastes are useful to us, for example, gums, resins, sandalwood oil, eucalyptus oil, tannin (found in the bark of many trees and used in the tanning of leather), rubber, and alkaloids (very poisonous compounds, some of which, like quinine, morphine, etc. are used as medicines).

Exercise Questions and Answers:

A. Answer these questions:

1. Discuss the importance of transport of various materials in the body.

Ans.

All living organisms must transport materials from one part of the body to another to sustain life. For example:

1. Food and oxygen are transported to all cells in the body for respiration and growth. 

2. Cells transport waste products to the organs responsible for their excretion.

2. In what ways are xylem and phloem important for transport in plants?

Ans.

Xylem and phloem combinedly called Vascular tissue is the main transport systems of plants. It transports water, minerals, and food throughout the plant. 

➢ Xylem carries water and minerals from the roots to the leaves.

➢ Phloem carries the food prepared by the leaves to different parts of the plant

3. Define and explain the process of transpiration.

Ans.

The process by which plants lose water as water vapours into the atmosphere is called transpiration. 

Plants use only a small amount of the water they absorb from the soil. The rest of the water escapes in the form of water vapours through the stomata. The opening and closing of stomatal apertures regulate the loss of water vapour from the leaves. Most of this loss takes place through the leaves but evaporation also occurs from stems, fruits, and flowers.

4. Briefly describe, diffusion, osmosis and translocation.

Ans.

Diffusion:

The molecular movement in gases or liquids which tends to result in their uniform distribution is called diffusion. In diffusion the molecules of a solute move from a solution where there is a higher concentration of its molecules to a solution where their concentration is low. The process of diffusion continues until the concentration of solute in all portions of the solution becomes equal (uniform). Diffusion involves the movement of molecules of gases, solutes and liquids other than water. 

Osmosis:

Osmosis is a special case of diffusion where the movement of a solver usually water, from a region of higher concentration to a region of lower concentration through a semi-permeable membrane.

Translocation.

The food prepared by the leaves is transported to all parts of the plant in the form of a solution through a process known as translocation. Translocation takes place mainly from leaf cell to different parts of plant through phloem tissues. However, in some plants, substances made in the roots are also transported to the leaves through the phloem tissue. 

5. Explain how the water is transported into the plant. Draw a diagram to show the movement of water through roots of a plant.

Ans:

The root hairs are delicate hair-like projections of the cells of the outer layer of a root. Root hairs are the absorptive organs of the plant. The film of water which surrounds the soil particles also surrounds the root hairs Soil water, with mineral salts dissolved in it, makes a very weak solution, and the cell sap of the root hair is stronger than it. Water, thus, moves from soil to root hair cells through osmosis, and this process occurs from cell to cell till it reaches the xylem vessels that carry it further upwards. With the help of this process, plant get their supply of water and mineral nutrients.

6. Which system is responsible for transport in humans? Name the organs that constitute this system.

Ans:

The process of diffusion is too slow to work in bigger animals. In such animals, including humans, a well-developed pick-up and delivery system, known as the circulatory system, is present. Thus, transport in humans is carried out by the circulatory system.

The circulatory system consists of:

• The heart
• Blood vessels
• Blood.

7. Define arteries and veins. What is the importance of capillaries in the circulatory system?

Ans. 

Arteries:

The blood vessels into which blood is pumped during a heartbeat are called arteries.

Viens:

The blood vessels that carry the blood back to the heart are called veins.

Importance of capillaries in the circulatory system:

Capillaries are the thinnest blood vessels, about as thick as hair. They have very thin walls. It is through these thin capillary walls that:

• Oxygen is picked up from the alveoli in the lungs.
• digested food is picked up in the small intestine.
• The oxygen and digested food are passed on to each cell of the body.
• Carbon dioxide and other wastes are picked up from every cell.
• Carbon dioxide is passed into the alveoli and wastes are passed into the kidneys. 

8. Name the constituents of blood. Discuss the importance of each constituent.

Ans.

The constituents of blood and their importance are as follows:

Plasma:

Plasma is the liquid part of the blood. It is yellowish in colour and contains about 90 percent water. It has food, wastes, enzymes, etc. dissolved in it. It also contains protein that helps the blood to clot.

Red blood cells (RBCs): These are disc-shaped cells. They contain a red-coloured protein called haemoglobin. It is this pigment that absorbs oxygen and transports it to the cells all over the body.

White blood cells (WBCs) These are slightly larger than red blood cells. They are fewer in number than red blood cells. Their main job is to fight against diseases by killing harmful bacteria and other foreign material. They can move on their own like Amoeba. This helps them to pass through the walls of blood vessels and to reach infected parts of the body.

Platelets; These are smaller than red blood cells. They help the blood to clot whenever the is a wound on the body. This blocks the flow of blood and prevents blood loss.

9. Enlist the functions of blood in human beings.

Ans. 

Functions of Blood:

• It carries oxygen to various parts of the body.
• It carries digested food materials to various parts of the body for distribution.
• It transports hormones and a number of other substances.
• It helps in preventing excessive bleeding by forming blood clot.
• It helps in maintaining a constant body temperature.
• it protects the body against invading germs.
• It transports waste materials to the excretory organs for excretion.

10. Define metabolism and excretion. Why is excretion important?

Ans.

Metabolism:

During life activities such as cellular respiration, several chemical reactions that take place in the body are known as metabolism.

Excretion:

The removal of waste products produced during metabolisms such as carbon dioxide, water, salts, urea, and uric acid from the body is called excretion.

Importance of excretion:

During the metabolism waste products, such as carbon dioxide, water, salts, urea, and uric acid are produced. A build-up of these wastes is harmful to the body. The excretory organs must remove these wastes. 

11. Discuss and draw a labelled diagram of the urinary system showing its various organs.

Ans.

The urinary system:

The urinary system is responsible for removing most of the wastes from the body in the form of urine. Urine consists of 95% water, 2.5% urea and 2.5% other waste products. The main organs of this system are the kidneys. 

Kidneys are located on each side of the backbone, just above the waist.

Function of kidneys:

The main function of the kidney is to filter wastes from the blood just like a filter paper to separate solid impurities from a solution. The kidneys work in the same way.

The kidneys consist of a large number of coiled tubes called nephrons.

The wastes collected in the kidneys form a liquid called urine. It passes from the kidneys through two tubes called ureters into an elastic sac called the urinary bladder. The bladder stores the urine until it is excreted from the body through the urethra. A human being passes out about 1.5 to 2.5 litres of urine every day. The kidneys must function properly to keep the body healthy.

12. How do plants excrete various kinds of waste products?

Ans. 

Plants also produce excretory materials in their cells though these are produced may more slowly than in animals. They have no excretory organs to expel them out. The different methods of excretion in plants are as follows:

• The waste gases-carbon dioxide, oxygen and water vapours, produced during respiration and photosynthesis, are expelled through the stomata of leaves and lenticels of the stem.
• Other waste products are converted into insoluble compounds which remain in the cells. When dead leaves, bark or any other parts fall off a tree, the waste products they contain are also removed. Some plants release waste products from their stems, these wastes including resin, gum and latex.