Chapter 6 Life Process Solutions
Question - 21 : - How is the amount of urine produced regulated?
Answer - 21 : - Amount of urine produced depends on the amount of excess water and dissolved waste present in the body. Other factors may be environment and ADH hormone which regulates the production of urine.
Question - 22 : - The kidneys in human beings are a part of the system for
Answer - 22 : -
(a) nutrition
(b) respiration.
(c) excretion.
(d) transportation
Answer
Answer is D excretion
The excretory system of human beings (Fig. 6.13) includes a pair of kidneys, a pair of ureters, a urinary bladder and a urethra. Kidneys are located in the abdomen, one on either side of the backbone. Urine produced in the kidneys passes through the ureters into the urinary bladder where it is stored until it is released through the urethra.
Question - 23 : - The xylem in plants are responsible for
Answer - 23 : -
(a) transport of water .
(b) transport of food.
(c) transport of amino acids.
(d) transport of oxygen.
Answer
In plants Xylem is responsible for transport of water hence the answer is a)
Question - 24 : - The autotrophic mode of nutrition requires
Answer - 24 : -
(a) carbon dioxide and water.
(b) chlorophyll.
(c) sunlight.
(d) all of the above
Answer
Autotrophic mode of nutrition requires carob-di-oxide, water, chlorophyll and sunlight from the preparation of food hence the answer is d) all of the above.
Question - 25 : - The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
Answer - 25 : -
(a) cytoplasm.
(b) mitochondria.
(c) chloroplast.
(d) nucleus
Answer
The breakdown of pyruvate to give carbon dioxide, water and energy takes place in mitochondria. Hence the answer is (b) mitochondria
Question - 26 : - How are fats digested in our bodies? Where does this process take place?
Answer - 26 : -
• The small intestine is the place for complete digestion of carbohydrates, fats and proteins. It receives the secretions of the liver and pancreas for this purpose.
• The food coming from the stomach is usually acidic in nature and it has to be made alkaline so that pancreatic enzymes can act on it. Bile juice produced in the liver accomplish this process.
• Fats are usually present in the intestine in the form of larger globules, which makes it difficult for enzymes to act on them. The bile salts helps in breaking down larger globules into smaller globules. The pancreas helps in secreting pancreatic juice, which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.
• The walls of the small intestine contains glands, which secretes intestinal juice. The enzymes present in it finally converts the proteins to amino acids, complex carbohydrates into glucose and finally fats into fatty acids and glycerol.
Question - 27 : - What is the role of saliva in the digestion of food?
Answer - 27 : - Food we intake is complex in nature, if it is to be absorbed from the alimentary canal then it has to be broken into smaller molecules. This process is mainly done with the help of biological catalysts called enzymes. The saliva contains an enzyme called salivary amylase that breaks down starch, which is a complex molecule to give sugar. The food is mixed thoroughly with saliva and moved around the mouth while chewing the muscular tongue. Hence saliva plays a pivotal in digestion and absorption of food.
Question - 28 : - What are the necessary conditions for autotrophic nutrition and what are its byproducts?
Answer - 28 : -
• The energy and carbon requirements of the autotrophic organism is obtained by the process of photosynthesis.
• It is defined as the process by which autotrophs take in substances from the outside surroundings and convert them into stored forms of energy.
• This substance is taken in the form of carbon dioxide and water, which is converted into carbohydrates in the presence of sunlight and chlorophyll.
• The main purpose of carbohydrates is to provide energy to the plant. The carbohydrates are not utilized immediately; but they are stored in the form of starch, which serves as an internal energy reserve.
• The stored energy can be used as and when required by the plant.
Question - 29 : - What are the differences between aerobic and anaerobic respiration?
Answer - 29 : - Name some organisms that use the anaerobic mode of respiration?
Answer
Aerobic respiration
• The process takes place in the presence of free oxygen
• The products of aerobic respiration are CO2, water and energy.
• The first step of aerobic respiration (glycolysis) takes place in cytoplasm while the next step takes place in mitochondria.
• The process of aerobic respiration takes place in all higher organisms.
• In this process complete oxidation of glucose takes place.
Anaerobic respiration
• The process takes place in the absence of the free oxygen.
• The products of anaerobic respiration are ethyl alcohol, CO2 and a little energy.
• Even in anaerobic respiration, the first step takes place in cytoplasm while the next step takes place in mitochondria.
• In this process the glucose molecules is incompletely broken down.
• The process of anaerobic respiration takes place in lower organism like yeast, some species of bacteria and parasites like tapeworm.
Question - 30 : - How are the alveoli designed to maximize the exchange of gases?
Answer - 30 : -
• The lung is an important part of the body. The passage inside the lungs divides into smaller and smaller tubes, which finally terminate in balloon-like structures, called as alveoli.
• The alveoli provide a surface where the exchange of gases can take place. The walls of the alveoli usually contains an extensive network of blood vessels. We know that, when we breathe in, we lift our ribs, flatten our diaphragm and chest cavity becomes larger.
• Because of this action, air is sucked into the lungs and fills the expanded alveoli.
• The blood brings the essential carbon dioxide from rest of the body and supply it to alveoli; the oxygen in the alveolar air is taken up by the blood in the alveolar blood vessels to be transported to the all other cells of the body. During normal breathing cycle, when air is taken in and let out, the lungs always contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and carbon dioxide to be released.