Life Processes

Intext Questions 1

Question 1

Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?

Answer

Multicellular organisms like humans require a more efficient circulatory system for transportation of oxygen as diffusion cannot transport oxygen to longer distances in the body. In multi-cellular organisms, all the cells may not be in direct contact with the surrounding environment. Thus, simple diffusion will not meet the requirements of all the cells. So, in multicellular organisms like humans, transport of oxygen through blood stream ensures its efficient supply to each cell of body.

Question 2

What criteria do we use to decide whether something is alive?

Answer

The presence of movement whether noticeable and visible or at a molecular level invisible to naked eye is the main criteria that we can use to decide whether something is alive or not.

Question 3

What are outside raw materials used for by an organism?

Answer

Outside raw materials used by autotrophs are carbon dioxide, water and sunlight. Besides these they also need other raw materials like nitrogen, phosphorus, iron, magnesium, etc. for building their body.

Outside raw materials used by heterotrophs are food, water and oxygen.

Question 4

What processes would you consider essential for maintaining life?

Answer

Processes considered essential for maintaining life are:

1. Breathing
2. Nutrition & Digestion
3. Transportation
4. Excretion

Intext Questions 2

Question 1

What are the differences between autotrophic nutrition and heterotrophic nutrition?

Answer

Question 2

Where do plants get each of the raw materials required for photosynthesis?

Answer

Plants take energy from sunlight, water from soil and carbon dioxide from air to carry out photosynthesis.

Question 3

What is the role of the acid in our stomach?

Answer

Hydrochloric acid performs the following functions in our stomach:

1. It creates an acidic medium which facilitates the action of the protein digesting enzyme called pepsin.
2. It kills any germs which may have entered along with the food.

Question 4

What is the function of digestive enzymes?

Answer

The digestive enzymes help to break complex food into their simpler form so that they are absorbed into the blood stream. For example, protein is broken into amino acids, carbohydrate is broken into glucose and fats are broken into fatty acids and glycerol.

Question 5

How is the small intestine designed to absorb digested food?

Answer

The inner lining of the small intestine has numerous finger-like projections called villi which increase the surface area for absorption. The villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body.

Intext Questions 3

Question 1

What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?

Answer

Terrestrial animals can breathe the oxygen in the atmosphere, but animals that live in water need to use the oxygen dissolved in water. Since the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms.

Question 2

What are the different ways in which glucose is oxidised to provide energy in various organisms?

Answer

The different ways in which glucose is oxidised to provide energy in various organisms are shown below:

Question 3

How is oxygen and carbon dioxide transported in human beings?

Answer

In human beings, the respiratory pigment is haemoglobin which has a very high affinity for oxygen. This pigment is present in the red blood corpuscles and is responsible for transportation of oxygen. Carbon dioxide is more soluble in water than oxygen is and hence is mostly transported in the dissolved form in our blood.

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 which finally terminate in balloon-like structures which are called alveoli. The alveoli provide an increased surface area where the exchange of gases can take place.

Intext Questions 4

Question 1

What are the components of the transport system in human beings? What are the functions of these components?

Answer

The components of the transport system in human beings are:

1. Blood
2. Heart
3. Blood vessels
4. Lymph

Question 2

Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?

Answer

Birds and mammals, constantly use energy to maintain their body temperature. Therefore, they need a highly efficient supply of oxygen to the body. The mixing of oxygenated and deoxygenated blood lowers the efficiency to supply oxygen. Therefore, it is necessary to separate oxygenated and deoxygenated blood in mammals and birds.

Question 3

What are the components of the transport system in highly organised plants?

Answer

Plant transport systems consists of two pathways that are constructed as independently organised conducting tubes. One, the xylem moves water and minerals obtained from the soil. The other, phloem transports products of photosynthesis from the leaves where they are synthesised to other parts of the plant.

Question 4

How are water and minerals transported in plants?

Answer

Water and minerals are transported in plants by Xylem vessels. 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. Water and minerals are transported in plants in following ways:

1. At the roots, cells in contact with the soil actively take up ions.
2. This creates a difference in the concentration of these ions between the root and the soil.
3. Water, therefore, moves into the root from the soil to eliminate this difference. This means that there is steady movement of water into root xylem, creating a column of water that is steadily pushed upwards.
4. As this pressure is not enough to push water very high, plants create a suction force through transpiration by losing water in the form of vapour from their aerial parts which pulls water higher up from the roots.

Question 5

How is food transported in plants?

Answer

Food is transported in plants by phloem tissues. The soluble food formed after photosynthesis and other materials like amino acids are translocated to all parts and also storage organs of plant. The translocation of food and other substances takes place in the sieve tubes with the help of adjacent companion cells both in upward and downward directions. The translocation in phloem is achieved by utilising energy.

Intext Questions 5

Question 1

Describe the structure and functioning of nephrons.

Answer

Nephron is the basic filtration unit in the kidney. It consists of a tubule which is connected with a collecting duct at one end and a cup shaped structure at the other end, called Bowman's capsule. Every Bowman's capsule contains a cluster of capillaries called glomerulus within the cup-shaped structure. The blood enters into glomerulus through afferent arteriole of renal artery and leaves it through efferent arteriole. This causes filtration of the blood. Then the filtrate passes into the tubular part of the nephron. Here, useful substances such as glucose, amino acids, salts and some water are re-absorbed into the blood by the capillaries surrounding the nephron tubule. The filtrate which remains after the re-absorption is called the urine, which is collected from nephron by the collecting duct to carry it to the urinary bladder and then to the urethra.

Question 2

What are the methods used by plants to get rid of excretory products?

Answer

The methods used by plants to get rid of excretory products are:

1. Oxygen and carbon dioxide are released through stomata.
2. Excess water is removed through transpiration.
3. Other wastes may be removed through dead tissues like falling leaves.
4. Waste products are also stored in cellular vacuoles, resins or gums.
5. Plants also excrete some waste substances into the soil around them.

Question 3

How is the amount of urine produced regulated?

Answer

The amount of urine produced is regulated by the amount of water re-absorbed and it depends on how much excess water there is in the body, and on how much of dissolved waste there is to be excreted.

Exercises

Question 1

The kidneys in human beings are a part of the system for

1. nutrition
2. respiration
3. excretion
4. transportation

Answer

excretion

Reason— Kidneys carry out filtration of blood and remove waste materials.

Question 2

The xylem in plants are responsible for

1. transport of water
2. transport of food
3. transport of amino acids
4. transport of oxygen

Answer

transport of water

Reason— Xylem vessels are responsible for transport of water in upward direction.

Question 3

The autotrophic mode of nutrition requires

1. carbon dioxide and water
2. chlorophyll
3. sunlight
4. all of the above

Answer

all of the above

Reason— Autotrophs make their food by using carbon dioxide and water in presence of chlorophyll and sunlight.

Question 4

The breakdown of pyruvate to give carbon dioxide, water and energy takes place in

1. cytoplasm
2. mitochondria
3. chloroplast
4. nucleus

Answer

mitochondria

Reason— Breakdown of pyruvate using oxygen takes place in the mitochondria.

Question 5

How are fats digested in our bodies? Where does this process take place?

Answer

Fats are present in the intestine in the form of large globules which makes it difficult for enzymes to act on them. Bile salts break them down into smaller globules increasing the efficiency of enzyme action. The pancreas secretes pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats. The fat is finally broken into fatty acids and glycerol.

The digestion of fats take place in small intestine.

Question 6

What is the role of saliva in the digestion of food?

Answer

The saliva contains an enzyme called salivary amylase that breaks down starch which is a complex molecule to give simple sugar. It also makes passage of food through oesophagus easier.

Question 7

What are the necessary conditions for autotrophic nutrition and what are its byproducts?

Answer

The necessary conditions for autotrophic nutrition are carbon dioxide, water, presence of sunlight and chlorophyll which are necessary for the process of photosynthesis.

The byproducts of photosynthesis are water and oxygen.

Question 8

What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

Answer

Some organisms that use the anaerobic mode of respiration are yeast, lactic acid bacteria and some parasitic worms like tape worm.

Question 9

How are the alveoli designed to maximise the exchange of gases?

Answer

The alveoli provide a large surface area for the exchange of gases to take place. The walls of the alveoli contain an extensive network of blood-vessels. The blood brings carbon dioxide from the rest of the body for release into the alveoli, and the oxygen in the alveolar air is taken up by blood in the alveolar blood vessels to be transported to all the cells in the body.

Question 10

What would be the consequences of a deficiency of haemoglobin in our bodies?

Answer

Hemoglobin deficiency, also known as anemia, is characterized by a decrease in the number of red blood cells or a lower concentration of hemoglobin in the blood. Hemoglobin deficiency can have serious consequences for our bodies, some of which are listed below:

1. Hemoglobin deficiency deprives the body of the oxygen it needs, leading to persistent fatigue, weakness and shortness of breath.
2. Due to inadequate oxygen supply to the brain we may may experience difficulty concentrating, memory problems, and decreased mental alertness.

Question 11

Describe double circulation of blood in human beings. Why is it necessary?

Answer

Double circulation is a process during which blood passes twice through the heart during one complete cycle through the human body. First, the deoxygenated blood is send to lungs and oxygenated blood from lungs reaches heart. This circulation is known as pulmonary circulation. Oxygenated blood that reaches the heart is send to whole body and the deoxygenated blood from different body parts is again brought to heart. This is known as systemic circulation.

Human beings constantly use energy to maintain their body temperature. Therefore, they need a highly efficient supply of oxygen to the body. The mixing of oxygenated and deoxygenated blood lowers the efficiency to supply oxygen. Therefore, it is necessary to separate oxygenated and deoxygenated blood

Question 12

What are the differences between the transport of materials in xylem and phloem?

Answer

Question 13

Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.

Answer

Structure and functioning of alveoli in the lungs and nephrons in the kidneys is compared below: