Question 1

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

Accepted Answer

Kidneys are the bean shaped reddish brown paired organs that serve in maintaining the fluid electrolyte balance and acid base balance of body through the process of urine formation. Excretion refers to removal of metabolic waste from body. This makes kidneys part of excretory system. Nutrition refers to obtaining the food to meet the energy requirement for growth and development. Respiration refers to the process that allows entry of oxygen from air to blood and exit of carbon dioxide from blood to air. Transportation refers to movement of materials, mainly nutrients and gases, from one organ to other.

Question 2

The xylem in plants are responsible for:

Accepted Answer

Xylem tissues are used for the transportation of water in plants.

Question 3

The autotrophic mode of nutrition requires:

Accepted Answer

Autotrophic organisms have the ability to form their own food. This is done with the help of water, carbon dioxide, chlorophyll and sunlight.

Question 4

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

Accepted Answer

The break down of pyruvate to give carbon dioxide, energy and water takes place in the presence of oxygen and is termed as aerobic respiration. This process takes place in the mitochondria of a cell.

Question 5

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

Accepted Answer

Fat digestion takes place in the small intestine. The alkaline secretion of the liver, bile, is carried to the small intestine by the bile duct. The process starts with emulsification (break down) of large fat globule by the salt of bile into smaller micelles to facilitate further enzymatic reaction and digestion process. The fat-digesting lipase enzyme in pancreatic juice and intestinal juices digest the fat in micelles into triacylglycerols and then fatty acids and glycerols. These fat digestion products are then absorbed by the intestinal mucosa and are carried to tissues by the lymphatic system and blood where they either serve as energy fuel or are stored after re-esterification.

Question 6

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

Accepted Answer

Salivary glands are present in the oral cavity that secrete saliva which is released into the mouth. Saliva contains bicarbonate and salivary amylase and serves to initiate the process of starch digestion into simple sugars by breaking the α-1, 4- glycosidic linkage of starch to release oligosaccharides.

Question 7

What are the necessary conditions for autotrophic nutrition and what are its by-products?

Accepted Answer

The autotrophic organisms are self-feeders that can synthesize the organic compounds using carbon dioxide as a source of carbon and water as an electron donor. Green plants are photoautotrophs that carry out photosynthesis, a process that requires atmospheric carbon dioxide, water, sunlight, and chlorophyll.The energy of sunlight is trapped by chlorophyll and is used to fix carbon dioxide into organic compounds (glucose) in the presence of water. These organic compounds are used by plants for their own growth and maintenance and stored in the form of starch that serves as a source of energy when required. Since water molecules serve as an electron donor, oxygen is produced during the process of photosynthesis as a by-product and is released into the air.

Question 8

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

Accepted Answer

The difference between aerobic and anaerobic respiration. Aerobic respiration Anaerobic respiration1. Aerobic respiration refers to complete breakdown of metabolic fuels in presence of oxygen.1. Anaerobic respiration is the process of partial breakdown of fuel (glucose) in absence of oxygen.2. It includes glycolysis, citric acid cycle and oxidative phosphorylation. The first two processes take place in the cytoplasm while last one occurs in mitochondria.2. Glycolysis is followed by ethanol fermentation (occurs in yeast) or lactic acid fermentation (in muscles and microbes like lactic acid bacteria). 3. The end products are carbon dioxide and water.3. End products of ethanol fermentation are ethanol and carbon dioxide; that of lactic acid fermentation are lactic acid4. Owing to complete oxidation of glucose, a large amount of energy is produced (36-38 ATP molecules)4. Incomplete oxidation of glucose does not release all stored energy and only 2 ATP molecules are produced.Anaerobic respiration is carried out by yeast and other anaerobic organisms like lactic acid bacteria, E. coli, Staphylococcus, Clostridium etc.

Question 9

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

Accepted Answer

Alveoli are pouch-like air sac that is made up of simple squamous epithelium. It has a thin cell wall to facilitate gaseous exchange. The presence of millions of alveoli in the lungs provides ample surface area to facilitate gaseous exchange between the air in alveoli and blood in surrounding capillaries. Oxygen diffuses across the alveolar and capillary wall into the bloodstream while carbon dioxide diffuses from blood across the mentioned walls into the alveoli.

Question 10

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

Accepted Answer

Haemoglobin molecule contains four polypeptide chains and four heme prosthetic groups. It serves as carrier of oxygen gas. Haemoglobin deficiency would decrease the oxygen carrying capacity of blood which in turn would cause breathing problems and lack of energy and weight loss.

Question 11

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

Accepted Answer

Mammals have a double circulatory system. This means that during a single cycle, the blood goes twice in the heart. There are two loops in which blood is circulated. One loop is oxygenated and the other is de-oxygenated. This double circulatory system is important because it ensures provision of oxygenated blood to the muscle and not a mixture of oxygenated and de-oxygenated blood. Hence, this system ensures efficient supply of oxygenated blood to the muscles.

Question 12

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

Accepted Answer

Difference between xylem and phloem transport: Xylem transport Phloem transport1. Xylem tissues include tracheids, vessels, fibres and parenchyma and serve in ascent of sap/water and minerals. 1. Phloem tissues is a composed of four elements namely, sieve tube elements, companion cell, phloem fibres and phloem parenchyma and serve in translocation of organic nutrients.  2. Due to defined source and sink relationship, the movement is unidirectional.  2. The movement is multidirectional as source sink relationship keeps changing. 3. Xylem transport is not influenced by metabolic inhibitors. 3. Phloem transport is inhibited by metabolic inhibitors. 4. Xylem vessels and tracheids are main component of transport.4. Sieve tube are main component of transport which are assisted by companion cells.5. Major driving forces are transpiration pull and diffusion. 5. Being active transport, it uses ATP.

Question 13

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

Accepted Answer

Alveoli and nephrons.No. Alveoli Nephrons 1. Alveoli are pouch-like air sacs that are made up of simple squamous epithelium.1. Nephrons are the elongated tubules that form an anatomical and functional unit of the kidney.  2. It has a thin cell wall to facilitate gaseous exchange.2. Each nephron has Bowman's capsule, proximal convoluted tubule, a loop of the nephron, distal convoluted tubule and the collecting ducts.  3. It is surrounded by blood capillaries. 3. Blood capillaries are present as glomerulus and peritubular capillaries.  4. Presence of millions of alveoli in lungs provide ample surface area to facilitate gaseous exchange between air in alveoli and blood in capillaries. Oxygen diffuses across the alveolar and capillary wall into the bloodstream while carbon dioxide diffuses from blood across the mentioned walls into the alveoli.4. It serves in fluid and electrolyte balance of the body through the process of urine formation. Each part performs different role in urine formation.

Chapter 6 : Life Processes