CLASS 10 BIOLOGY NCERT LIFE PROCESS, CONTROL AND CO ORDINATION SOLUTION

                           SCIENCE 

                                        CLASS 1O

                         CHAPTER 6 ( LIFE PROCESS  )

Question 1: 

THE kidneys in human being are a part of the system for 

a) nutition 

b) respiration 

c)excretion 

d)transportation 

Answer 1: 

in human beings ,the kidneys are a part of the system of excretion.

Question 2:

the xylem in plants are responsible for:

a) transport of water 

b)transport of food 

c) transport of amino acid 

d)tranport of oxygen 

Answer 1: 

in a plant xylen is responsible for transport of water .

Question 3:

the autotrophic mode of nutrition required :

a) carbon dioxide and water 

b) chlorophyll

c) sunlight 

d) all of the above 

Answer d

the autotrophic mode of nutrition required  carbon dioxide and water  chlorophyll  sunlight 

all of the above 

Question 4:

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

(a)  cytoplasm.

(b)  mitochondria.

(c)  chloroplast.

(d)  nucleus.

Answer 4:

(b)   The breakdown of pyruvate to give carbon dioxide, water and energy takes place in mitochondria.

Question 5:

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

Answer 5:

Fats are present in the form of large globules in the small intestine. The small intestine gets the secretions in the form of bile juice and pancreatic juice respectively from the liver and the pancreas. The bile salts (from the liver) break down the large fat globules into smaller globules so that the pancreatic enzymes can easily act on them. This is referred to as emulsification of fats. It takes place in the small intestine.

Question 6:

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

Answer 6:

Saliva is secreted by the salivary glands, located under the tongue. It makes the food soft for easy swallowing. It contains a digestive enzyme called salivary amylase, which breaks down starch into sugar.

Question 7:

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

Answer 7:

Autotrophic nutrition takes place through the process of photosynthesis. Carbon dioxide, water, chlorophyll pigment, and sunlight are the necessary conditions required for autotrophic nutrition. Carbohydrates (food) and O2 are the by- products of photosynthesis.

𝐶ℎ𝑙𝑜𝑟𝑜𝑝ℎ𝑦𝑙𝑙 𝑎𝑛𝑑 𝑆𝑢𝑛𝑙𝑖𝑔ℎ𝑡

6CO2 + 6H2O →  C6H12O6 + 6O2

Question 8:

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

Answer 8:

Difference between Aerobic respiration and Anaerobic respiration:

Aerobic respiration		Anaerobic respiration
1.	It occurs in the presence of O2.	1.	It occurs in the absence of O2
2.	It involves the exchange of gases between the organism and the outside environment.	2.	Exchange of gases is absent.
3.	It   occurs   in    cytoplasm   and mitochondria.	3.	It occurs only in cytoplasm.
4.	It always releases CO2 and H2O.	4.	It produces alcohols and CO2.
5.	It yields large amount of energy.	5.	Energy released is very low.

Anaerobic respiration occurs in the roots of some waterlogged plants, some parasitic worms, animal muscles and some micro-organisms such as yeasts.

Question 9:

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

Answer 9:

The alveoli are the small balloon-like structures present in the lungs. The walls of the alveoli consist of extensive network of blood vessels. Each lung contains 300−350 million alveoli, making it a total of approximately 700 million in both the lungs. The alveolar surface when spread out covers about 80 m2 area. This large surface area makes the gaseous exchange more efficient.

Question 10:

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

Answer 10:

Haemoglobin is the respiratory pigment that transports oxygen to the body cells for cellular respiration. Therefore, deficiency of haemoglobin in blood can affect the oxygen supplying capacity of blood. This can lead to deficiency of oxygen in the body cells. It can also lead to a disease called anaemia.

Question 11:

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

Answer 11:

Because both oxygen and carbon dioxide have to be transported by the blood, the heart has different chambers to prevent the oxygen-rich blood from mixing with the blood containing carbon dioxide. The human heart is divided into four chambers − the right atrium, the right ventricle, the left atrium and the left ventricle.

Oxygen-rich blood from the lungs comes to the thin-walled upper chamber of the heart on the left, the left atrium. The left atrium relaxes when it is collecting this blood. It then contracts, while the next chamber, the left ventricle, expands, so that the blood is transferred to it. When the muscular left ventricle contracts in its turn, the blood is pumped out to the body.

De-oxygenated blood comes from the body to the upper chamber on the right, the right atrium, as it expands. As the right atrium contracts, the corresponding lower chamber, the right ventricle, dilates. This transfers blood to the right ventricle, which in turn pumps it to the lungs for oxygenation.

During this process blood goes twice through the heart. That’s why it is known as double circulation.

Double Circulation is necessary:

The separation of oxygenated and de-oxygenated blood allows a more efficient supply of oxygen to the body cells. This efficient system of oxygen supply is very useful in warm-blooded animals such as human beings. As we know, warm- blooded animals have to maintain a constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment. Hence, they require more O2 for more respiration so that they can produce more energy to maintain their body temperature.

Thus, the circulatory system of humans is more efficient because of the double circulatory heart.

Question 12:

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

Answer 12:

Difference between Xylem and Phloem:

Xylem		Phloem
1.	Xylem    tissue   helps   in    the transport of water and minerals.	1.	Phloem   tissue   helps    in    the transport of food.
2.	Water  is   transported  upwards from roots to all other plant parts.	2.	Food is transported in both upward and downward directions.
3.	Transport in xylem occurs with the help of simple physical forces such as transpiration pull.	3.	Transport of food in phloem requires energy in the form of ATP.

Question 13:

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

Answer 13:

Alveoli		Nephron
1.	Alveoli are tiny balloon- like structures present inside the lungs.	1.	Nephrons are tubular structures present inside the kidneys.
2.	The walls of the alveoli are one cell thick and it contains an extensive network of blood capillaries.	2.	Nephrons are made of glomerulus, bowman’s capsule, and a long renal tube. It also contains a cluster of thin walled capillaries.
3.	The exchange of O2 and CO2 takes place between the blood of the capillaries that surround the alveoli and the gases present in the alveoli. Alveoli are the site of gaseous exchange.	3.	The blood enters the kidneys through the renal artery which branches into many capillaries in the glomerulus. The water and solute are transferred to the nephron at Bowman’s capsule. Then the filtrate moves through the proximal tubule, distal tubule and collecting duct. The collecting duct collects the urine from many nephrons and passes it to the ureter. During the flow of filtrate, some substances such as glucose, amino acids, and water are selectively reabsorbed. Nephrons are the basic filtration unit.

Question 1:

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

Answer 1:

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.

Question 2:

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

Answer 2:

Any visible movement such as walking, breathing, or growing is generally used to decide whether something is alive or not. However, a living organism can also have movements, which are not visible to the naked eye. Therefore, the presence of molecular movement inside the organisms used to decide whether something is alive or not.

Question 3:

What are outside raw materials used for by an organism?

Answer 3:

An organism uses outside raw materials mostly in the form of food (Since life on earth depends on carbon based molecules, most of these food sources are also carbon-based) and oxygen. The raw materials required by an organism can be quite varied depending on the complexity of the organism and its environment.

Question 4:

What processes would you consider essential for maintaining life?

Answer 4:

Life processes such as nutrition, respiration, transportation, excretion, etc. are essential for maintaining life.

Question 1:

What  are  the  differences  between  autotrophic  nutrition  and  heterotrophic nutrition?

Answer 1:

Autotrophic nutrition		Heterotrophic nutrition
1.	Food is synthesised from simple inorganic raw materials such as CO2 and water.	1.	Food is obtained directly or indirectly from autotrophs. This food is broken down with the help of enzymes.
2.	Presence     of   green     pigment (chlorophyll) is necessary.	2.	No pigment is required in this type of nutrition.
3.	Food   is   generally   prepared during day time.	3.	Food  can  be  prepared  at  all times.
4.	All green plants and some bacteria have this type of nutrition.	4.	All animals and fungi have this type of nutrition.

Question 2:

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

Answer 2:

The following raw materials are required for photosynthesis:

Ø The raw material CO2 enters from the atmosphere through stomata.

Ø Water is absorbed from the soil by the plant roots.

Ø Sunlight, an important component to manufacture food, is absorbed by the chlorophyll and other green parts of the plants.

Question 3:

What is the role of the acid in our stomach?

Answer 3:

Role of the acid (HCl) in our stomach:

Ø Kills germs present in the food.

Ø Makes the food acidic, so that pepsin can digest protein.

Question 4:

What is the function of digestive enzymes?

Answer 4:

Digestive enzymes such as amylase, lipase, pepsin, trypsin, etc. help in the breaking down of complex food particles into simple ones. These simple particles can be easily absorbed by the blood and thus transported to all the cells of the body.

Question 5:

How is the small intestine designed to absorb digested food?

Answer 5:

The small intestine has millions of tiny finger-like projections called villi. These villi increase the surface area for food absorption. Within these villi, many blood vessels are present that absorb the digested food and carry it to the blood stream. From the blood stream, the absorbed food is delivered to each and every cell of the body.

Question 1:

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

Answer 1:

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. Therefore, unlike aquatic animals, terrestrial animals do not have to show various adaptations for better gaseous exchange.

Question 2:

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

Answer 2:

Glucose is first broken down in the cell cytoplasm into a three carbon molecule called pyruvate. Pyruvate is further broken down in the following ways to provide energy:

Question 3:

How is oxygen and carbon dioxide transported in human beings?

Answer 3:

Haemoglobin transports oxygen molecule to all the body cells for cellular respiration. The haemoglobin pigment present in the blood gets attached to O2 molecules that are obtained from breathing. It thus forms oxyhaemoglobin and the blood becomes oxygenated. This oxygenated blood is then distributed to all the body cells by the heart. After giving away O2 to the body cells, blood takes CO2 which is the end product of cellular respiration. Now the blood becomes de- oxygenated.

Since haemoglobin pigment has less affinity for CO2, CO2 is mainly transported in the dissolved form. This de-oxygenated blood gives CO2 to lung alveoli and takes O2 in return.

Question 4:

How are the lungs designed in human beings to maximise the area for exchange of gases?

Answer 4:

The exchange of gases takes place between the blood capillaries that surround the alveoli and the gases present in the alveoli. Thus, alveoli are the site for exchange of gases. The lungs get filled up with air during the process of inhalation as ribs are lifted up and diaphragm is flattened. The air that is rushed inside the lungs fills the numerous alveoli present in the lungs. Each lung contains 300-350 million alveoli. These numerous alveoli increase the surface area for gaseous exchange making the process of respiration more efficient.

Question 1:

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

Answer 1:

The main components of the transport system in human beings are the heart, blood, and blood vessels.

Ø Heart pumps oxygenated blood throughout the body. It receives deoxygenated blood from the various body parts and sends this impure blood to the lungs for oxygenation.

Ø Blood is a fluid connective tissue, it helps in the transport of oxygen, nutrients, CO2, and nitrogenous wastes.

Ø Blood vessels (arteries, veins, and capillaries) carry blood either away from the heart to various organs or from various organs back to the heart.

Question 2:

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

Answer 2:

Warm-blooded animals such as birds and mammals maintain a constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment. Hence, these animals require more oxygen (O2) for more cellular respiration so that they can produce more energy to maintain their body temperature.

Thus, it is necessary for them to separate oxygenated and de-oxygenated blood, so that their circulatory system is more efficient and can maintain their constant body temperature.

Question 3:

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

Answer 3:

In highly organised plants, there are two different types of conducting tissues −

xylem and phloem.

Ø Xylem conducts water and minerals obtained from the soil (via roots) to the rest of the plant.

Ø Phloem transports amino acids and food materials from the leaves to different parts of the plant body.

Question 4:

How are water and minerals transported in plants?

Answer 4:

The components of xylem tissue (tracheids and vessels) of roots, stems and leaves are interconnected to form a continuous system of water – conducting channels that reaches all parts of the plant. Transpiration creates a suction pressure, as a result of which water is forced into the xylem cells of the roots. Then there is a steady movement of water from the root xylem to all the plant parts through the interconnected water – conducting channels.

Question 5:

How is food transported in plants?

Answer 5:

Phloem transports food materials from the leaves to different parts of the plant body. The transportation of food in phloem is achieved by utilizing energy from ATP. As a result of this, the osmotic pressure in the tissue increases causing water to move into it. This pressure moves the material in the phloem to the tissues which have less pressure. This is helpful in moving materials according to the needs of the plant. For example, the food material, such as sucrose, is transported into the phloem tissue using ATP energy.

Question 1:

Describe the structure and functioning of nephrons.

Answer 1:

Nephrons are the basic filtering units of kidneys. Each kidney possesses large number of nephrons, approximately 1-1.5 million. The main components of the nephron are glomerulus, Bowman’s capsule, and a long renal tubule.

Functioning of a nephron:

Ø The blood enters the kidney through the renal artery, which branches into many capillaries associated with glomerulus.

Ø The water and solute are transferred to the nephron at Bowman’s capsule.

 Ø In the proximal tubule, some substances such as amino acids, glucose, and salts are selectively reabsorbed and unwanted molecules are added in the urine.

Ø The filtrate then moves down into the loop of Henle, where more water is absorbed.

Ø From here, the filtrate moves upwards into the distal tubule and finally to the collecting duct. Collecting duct collects urine from many nephrons.

Ø The urine formed in each kidney enters a long tube called ureter. From ureter, it gets transported to the urinary bladder and then into the urethra.

Question 2:

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

Answer 2:

Plants use completely different strategies for excretion than those of animals. They can get rid of excess water by transpiration. For other wastes, plants use the fact that many of their tissues consist of dead cells, and that they can even lose some parts such as leaves. Many plant waste products are stored in cellular vacuoles. Waste products may be stored in leaves that fall off. Other waste products are stored as resins and gums, especially in old xylem. Plants also excrete some waste substances into the soil around them.

Question 3:

How is the amount of urine produced regulated?

Answer 3:

The amount of urine produced depends on the amount of excess water and dissolved wastes present in the body. Some other factors such as habitat of an organism and hormone such as Antidiuretic hormone (ADH) also regulates the amount of urine produced.

                       CHAPTER 7 (CONTROL AND CO ORDINATION )

Question 1: 

Which of the following is a plant hormone ?

a) insulin 

b) thyroxin

c) oestrogen

d) cytokinin

Answer 4: cytokinin is a plant harmone 

Question 2:

the gap between two neuron is called a 

a) dendrite

b) synapse

c) axon 

d) impulse

Answer b synapse 

Question 3:

the brain is responsible for 

a) thinking

b) regulating the heart beat 

c) balacing the body 

d) all of the above 

Answer d all of the above 

Question 4:

What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?

Answer 4:

Receptors are sensory structures (organs/tissues or cells) present all over the body. The receptors are either grouped in case of eye or ear, or scattered in case of skin.

Functions of receptors:

Ø They sense the external stimuli such as heat or pain.

Ø They also trigger an impulse in the sensory neuron which sends message to the spinal cord.

When the receptors are damaged, the external stimuli transferring signals to the brain are not felt. For example, in the case of damaged receptors, if we accidentally touch any hot object, then our hands might get burnt as damaged receptors cannot perceive the external stimuli of heat and pain.

Question 5:

Draw the structure of a neuron and explain its function.

Answer 5:

Neurons are the functional units of the nervous system. The three main parts of a neuron are axon, dendrite and cell body.

Functions of the three parts of a neuron:

Ø Axon: It conducts messages away from the cell body.

Ø Dendrite: It receives information from axon of another cell and conducts the messages towards the cell body.

Ø Cell body: It contains nucleus, mitochondria, and other organelles. It is mainly concerned with the maintenance and growth.

 Question 6:

How does phototropism occur in plants?

Answer 6:

The movement of plant in response to light is called phototropism. Stem shows positive phototropism as follows:

When growing plants detect light, a hormone called auxin, synthesised at the shoot tip, helps the cells to grow longer. When light is coming from one side of the plant, auxin diffuses towards the shady side of the shoot. This concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light. Thus, the plant appears to bend towards light.

  Question 7:

Which signals will get disrupted in case of a spinal cord injury?

Answer 7:

The reflex arc connections between the input and output nerves meet in a bundle in the spinal cord. In fact, nerves from all over the body meet in a bundle in the spinal cord on their way to the brain. In case of any injury to the spinal cord, the signals coming from the nerves as well as the signals coming to the receptors will be disrupted.

Question 8:

How does chemical coordination occur in plants?

Answer 8:

Animals have a nervous system for controlling and coordinating the activities of the body. But plants have neither a nervous system nor muscles.

Plants respond to stimuli by showing movements. The growth, development, and responses to the environment in plants is controlled and coordinated by a special class of chemical substances known as hormones. These hormones are produced in one part of the plant body and are translocated to other needy parts. For example, a hormone produced in roots is translocated to other parts when required. The five major types of phytohormone are auxins, gibberellins, cytokinins, abscisic acid, and ethylene. These phytohormones are either growth promoters (such as auxins, gibberellins, cytokinins, and ethylene) or growth inhibitors such as abscisic acid.

Question 9:

What is the need for a system of control and coordination in an organism?

Answer 9:

The maintenance of the body functions in response to changes in the body by working together of various integrated body systems is known as coordination. All the movements that occur in response to stimuli are carefully coordinated and controlled. In animals, the control and coordination movements are provided by nervous and muscular systems. The nervous system sends messages to and away from the brain. The spinal cord plays an important role in the relay of messages. In the absence of this system of control and coordination, our body will not be able to function properly.

For example, when we accidentally touch a hot utensil, we immediately withdraw our hand. In the absence of nerve transmission, we will not withdraw our hand and may get burnt.

Question 10:

How are involuntary actions and reflex actions different from each other?

Answer 10:

Involuntary actions cannot be consciously controlled. For example, we cannot consciously control the movement of food in the alimentary canal or pumping of blood through heart. These actions are however directly under the control of the brain. On the other hand, the reflex actions such as closing of eyes immediately when bright light is focused show sudden response and do not involve any thinking. This means that unlike involuntary actions, the reflex actions are not under the control of brain.

 Question 11:

Compare  and  contrast  nervous  and  hormonal  mechanisms  for  control  and coordination in animals.

Answer 11:

Nervous system mechanism		Hormonal system mechanism
1.	The information is conveyed in the form of electric impulse.	1.	The information is conveyed in the form of chemical messengers.
2.	The axons and dendrites transmit the information through a coordinated effort.	2.	The information is transmitted or transported through blood.
3.	The flow of information is rapid and the response is quick.	3.	The  information  travels  slowly and the response is slow.
4.	Its effects are short lived.	4.	It has prolonged effects.

 Question 12:

What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?

Answer 12:

Movement in sensitive plants		Movement in our legs
1.	The movement that takes place in a sensitive plant such as Mimosa pudica occurs in response to touch (stimulus).	1.	Movement  in  our  legs  is  an example of voluntary actions.
2.	For this movement, the information is transmitted from cell to cell by electrochemical signals as plants do not have any specialised tissue for conduction of impulses.	2.	The signal or messages for these actions are passed to the brain and hence are consciously controlled.
3.	For this movement to occur, the plant cells change shape by changing the amount of water in them.	3.	In animal muscle cells, some proteins are found which allow the movement to occur.

Question 1:

What is the difference between a reflex action and walking?

Answer 1:

Ø A reflex action is a rapid, automatic response to a stimulus. It does not involve any thinking. For example, we close our eyes immediately when the bright light is focused.

Ø Walking, on the other hand, is a voluntary action. It is under our conscious control.

Question 2:

What happens at the synapse between two neurons?

Answer 2:

A very small gap that occurs between the last portion of axon of one neuron and the dendrite of the other neuron is known as a synapse. It acts as a one way valve to transmit impulses in one direction only.

 This one-directional transfer of impulses occurs as the chemicals are produced in only one side of the neuron i.e., the axon’s side. From axon, the impulses travel across the synapse to the dendrite of the other neuron.

Question 3:

Which part of the brain maintains posture and equilibrium of the body?

Answer 3:

Cerebellum,  a  part  of  hindbrain  is  responsible  for  maintaining  posture  and equilibrium of the body.

 Question 4:

How do we detect the smell of an agarbatti (incense stick)?

Answer 4:

The thinking part of our brain is the forebrain. It has separate areas that are specialized for hearing, smelling, sight, taste, touch, etc. The forebrain also has regions that collect information or impulses from the various receptors. When the smell of an incense stick reaches us, our forebrain detects it. Then, the forebrain interprets it by putting it together with the information received from other receptors and also with the information already stored in the brain.

 Question 5:

What is the role of the brain in reflex action?

Answer 5:

Reflex actions are sudden responses, which do not involve any thinking. For example, when we touch a hot object, we withdraw our hand immediately without thinking as thinking may take time which would be enough to get us burnt. The sensory nerves that detect the heat are connected to the nerves that move the muscles of the hand. Such a connection of detecting the signal from the nerves (input) and responding to it quickly (output) is called a reflex arc. The reflex arcs

–connections present between the input and output nerves − meet in a bundle in

the spinal cord.

 Reflex arcs are formed in the spinal cord and the information (input) reaches the brain. The brain is only aware of the signal and the response that has taken place. However, the brain has no role to play in the creation of the response.

Question 1:

What are plant hormones?

Answer 1:

Plant hormones or phytohormones arenaturally-occurring organic substances. These are synthesized in one part of the plant body (in minute quantities) and are translocated to other parts when required. The five major types of phytohormones are auxins, gibberellins, cytokinins, abscisic acid and ethylene.

Ø Gibberellins help in the growth of the stem.

Ø Auxins help in the growth of the stem.

Ø Cytokinins promote cell division.

Ø Abscisic acid is one example of a hormone which inhibits growth.

Question 2:

How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?

Answer 2:

Ø The movement of leaves of the sensitive plant, Mimosa pudica or “touch me not”, occurs in response to touch or contact stimuli. This is done by plant cells by changing the amount of water in leaves. This movement is independent of growth.

Ø The movement of shoot towards light is known as phototropism. This type of movement is directional and is growth dependent.

Question 3:

Give an example of a plant hormone that promotes growth.

Answer 3:

Examples of plants growth hormones:

Ø Gibberellins help in the growth of the stem.

Ø Auxins help in the growth of the stem.

Ø Cytokinins promote cell division.

Question 4:

How do auxins promote the growth of a tendril around a support?

Answer 4:

These tendrils are sensitive to touch. When they come in contact with any support, auxin (a growth hormone) diffuses from the part of the tendril in contact with the object to other side, which is not in the contact. Therefore the part of the tendril in the contact with the object does not grow as rapidly as the part of the tendril away from the object. This causes the tendril to circle around the object and thus cling to it.

 Question 5:

Design an experiment to demonstrate hydrotropism.

Answer 5:

Take two small beakers and label them as A and B. Fill beaker A with water. Now make a cylindrical-shaped roll from a filter paper and keep it as a bridge between beaker A and beaker B, as shown in the figure. Attach few germinating seeds in the middle of the filter paper bridge. Now, cover the entire set-up with a transparent plastic container so that the moisture is retained.

Observation:

The roots of the germinating seeds will grow towards beaker A.

Question 1:

How does chemical coordination take place in animals?

Answer 1:

Chemical coordination takes place in animals with the help of hormones. Hormone is the chemical messenger that regulates the physiological processes in living organisms. It is secreted by glands. The regulation of physiological processes and control and coordination by hormones comes under the endocrine system. The nervous system along with the endocrine system in our body controls and coordinates the physiological processes.

Question 2:

Why is the use of iodised salt advisable?

Answer 2:

Iodine stimulates the thyroid gland to produce thyroxin hormone. It regulates carbohydrate, fat, and protein metabolism in our body. Deficiency of this hormone results in the enlargement of the thyroid gland. This can lead to goitre, a disease characterized by swollen neck. Therefore, iodised salt is advised for normal functioning of the thyroid gland.

 Question 3:

How does our body respond when adrenaline is secreted into the blood?

Answer 3:

Adrenalin is a hormone secreted by the adrenal glands in case of any danger or emergency or any kinds of stress. It is secreted directly into the blood and is transported to different parts of the body.

When secreted in large amounts, it speeds up the heartbeat and hence supplies more oxygen to the muscles. The breathing rate also increases due to contractions of diaphragm and rib muscles. It also increases the blood pressure. All these responses enable the body to deal with any stress or emergency.

Question 4:

Why are some patients of diabetes treated by giving injections of insulin?

Answer 4:

Diabetes is a disease in which the level of sugar in the blood is too high. Insulin, a hormone secreted by the pancreas, helps in regulating the blood sugar levels. This is the reason why diabetic patients are treated by giving injections of insulin.