Maharashtra Board Class 9 Science Solution Chapter 15 – Life Processes in Living Organisms
Balbharati Maharashtra Board Class 9 Science Solution Chapter 15: Life Processes in Living Organisms. Marathi or English Medium Students of Class 9 get here Life Processes in Living Organisms full Exercise Solution.
Std |
Maharashtra Class 9 |
Subject |
Science Solution |
Chapter |
Life Processes in Living Organisms |
1.) Match the following pairs.
Ans:
1) Growth of pollen tube towards ovule: Chemotropic movement
2) Growth of shoot system: Phototropic movement
3) Growth of root system: Gravitropic movement
4) Growth towards water: Hydrotropic movement
2.) Complete the paragraph.
( Nerve, muscle cells, impulse, dendrite, synapse, axon, reflex action, cell body)
Ans:
The milk was on the stove. Rasika was engrossed watching television. She smelled something burning. She ran towards the kitchen. The milk was boiling over. She held the vessel with her bare hands but, screaming, she let it go at once. The activity was controlled by nerve cells. Special ends of dendrites in these cells collected the information, from where it was transferred to the cell body and then towards the terminal end of the axon. The chemicals produced at the terminal end passed through the minute space i.e. synapse. In this way, impulse were conducted in the body and the process of reflex action was completed by conducting the impulses from nerve to muscle cells.
3.) Write the notes on
a) Root pressure
Ans:
- The water and minerals from the soil are in contact with the root cells. As there is difference in concentration in the cells on root surface water and minerals enters through it.
- Due to absorption of water and minerals the cells became turgid due to which there will be pressure created which is exerted on the adjacent cell and that pressure exerted is called as the root pressure.
- Due to the root pressure water and minerals reach to the xylem of the roots and to reduce the difference in concentration they will be pushed forward continuously. Due to this continuous movement water column is formed and would be pushed shed.
- And in this way because of root pressure created the water will lift in the upper part of plants like shrubs, small plants and small trees.
b) Transpiration
Ans:
Transpiration is the process in which loss of water through leaves of plants takes place. There are many internal and external factors which affects the transpiration.
Following are the internal factors involved:
- Leaf area: If there is large leaf area then there will be more loss in water through transpiration.
- Leaf structure: The thick cuticle, wax layer cells may reduces the water loss through transpiration process.
- In this way, the internal factors involved may increase or decrease the rate of transpiration in plants.
- Transpiration helps in absorption of water and minerals and distribute it to the all parts of plant body and due to root pressure the water lifted up in plants during night time also.
Following are the external factors involved:
- Atmospheric humidity: Higher is the atmospheric humidity lower is the rate of transpiration because due to humidity there will be no more water required for plants.
- Temperature: As the temperature is increases there will be more need of water for plants and hence the rate of transpiration also increase. In summer days due to high temperature the rate of transpiration also increases.
- Wind velocity: As the velocity of wind increases its rate of transpiration also increases.
- Water supply: If there is low water level in the soil then it decreases the rate of transpiration as no water is pulled up through root pressure.
- Transpiration helps in upward movement of water in tall trees and distribute water throughout the plant body.
- Due to transpiration the surface of leaves becomes cool and maintain their texture and greenery.
- Transpiration get affected when the water absorption by root get affected due to insufficient root pressure.
c) Nerve cell
Ans:
- Nerve cell is also termed as neurons which conducts the impulse from one place to another in the body and consist of three main parts namely cell body, axon and dendrites.
- Neurons are the structural and functional units of the nervous system. They are the largest cells in the human body and having ability to conduct electrochemical impulses also.
- The supporting cells to the neurons are the neuroglia together with nerve cells called as nerves.
- The ends of the dendrites collects the surrounding information and electric impulses are generated which are conducted from dendrites to cell body, cell body to axon and then axon to its terminal.
- And then transferred from one nerve cell to next the terminal of axon stimulates the nerve cell to secret some chemicals which are passed through small spaces called as synapse and finally impulse is generated in the next dendrites.
- In this way, impulses are conducted from nerve cells to the muscles or glands.
d) Human brain
Ans:
- Human brain is the part of central nervous system which is extremely delicate and highly evolved. It is located in the cranial cavity and it is the main controlling part of central nervous system.
- The brain of an adult human weighs about 1300-1400 grams consisting of 100 billion neurons.
- The left part of brain controlled the right part of our body and speech, conversation, writing, logical thinking etc. While right side of brain controlled the left part of our body and controls artistic abilities.
Cerebrum:
- Cerebrum is the largest part of our brain consisting of two cerebral hemispheres. Through tough fibres and nerve tracts these hemispheres are joined with each other.
- As Cerebrum occupies two third portion of the brain hence it is also called as large brain. It has convolutions which increases the surface area of the cerebrum due to which large number of nerve cells get accomoded
Cerebellum:
- Cerebellum is the smaller part of brain which is located below the cerebrum behind the cranial cavity.
- The surface of cerebellum shows shallow grooves instead of the deep convolutions.
Medulla oblongata:
- The hind most part of the brain is the medulla oblongata. On the upper side of medulla oblongata there are triangular swollen structures which we called as pyramids.
- And it continues the downwards as the spinal cord.
e) Reflex action
Ans:
- Reflex action is the an intermediate and an involuntary response given to the stimulus from the environment. Sometimes we give quick response to any thing happened without thinking then it will be the stimulus from the surrounding.
- Reflex action is the automatic stimulus given the by the brain. The sensory nerves are connected to nerves which are moving the muscles and that connection is called as reflex arc.
- In spinal cord these reflex arc bundles meet each other. The signal and response reach to the brain. For example: when we touch to the hot body we suddenly withdraw our hands because of reflex action.
4.) Name the hormones of the following endocrine glands and the function of each gland.
a) Pituitary gland
Ans:
Pituitary gland is the master gland as it secrets growth hormone and also other hormones which regulate the secretion of other endocrine glands.
The hormones secreted by pituitary gland with their functions are as follows.
- Prolactin : It is hormone secreted by pituitary gland and which is responsible for growth of mammary glands and formation of milk.
- TSH: It is the hormone secreted by pituitary gland and which is responsible for synthesis and release of thyroid hormone.
- ACTH: It is responsible for stimulation of synthesis and secretion of steroid hormones.
- Vasopressin : It is called as anti-diuretic hormone as it prevents loss of water through urine and it is secreted by pituitary gland.
b) Thyroid
Ans:
- Thyroid gland secrets the hormone thyroxin which has following functions.
- The thyroxin hormone secreted by thyroid gland helps in working of kidney and also urine formation.
- It helps in controlling BMR.
- The hormone thyroxin also regulates the mental, physical and sexual growth.
- It regulates growth of CNS and bones.
- The metabolism and carbohydrates are also regulates by the hormone thyroxin secreted by thyroid gland.
c) Adrenal gland
Ans:
- The adrenal gland is located on the anterior part of each kidney.
- The hormones secreted by adrenal gland are adrenalin and nor adrenalin, corticosteroids.
- They controls the behaviour of person during crisis and emotional situations.
- It helps in stimulating heart and it’s conducting tissue and also the metabolic processes.
- It mainly maintains the balance of Na+ and K+ and also helps in stimulating metabolism.
d) Thymus
Ans:
- The thymus gland Is located in thoracic cage near the heart and which secrets peptide hormones which are called as thymosins which helps in separation of T- lymphocytes and helps in promoting antibodies.
- As thymus is degenerated in old people hence their immune response is weak.
- Thymosin controls the cells which give rise to immunity.
e) Testes
Ans:
- Testes are located in the scrotum and which secrets the hormone androgen which helps in development, maturation and functioning of the male accessory sex organs such as vas deference and the seminal vesicles.
- The hormone secreted by testis is testosterone which stimulates growth of secondary sexual characters like beard, mustache, hoarse voice, etc in men
- It stimulates the muscular growth and growth of the facial hairs, low pitch voice and role in spermatogenesis.
- It helps in anabolism of protein and carbohydrates.
f) Ovary
Ans:
- Ovary is located on the either side of uterus in women and it secrets the hormone oestrogen and progesterone which has the following functions.
- It stimulates the growth of endometrium.
- Also stimulates the secondary sexual characters in women.
- And it prepares the endometrium for conception and helps in maintaining the pregnancy.
5.) Draw and label the diagrams.
a) Human brain:
b) Nephron:
c) Nerve cell:
d) Human excretory system:
6.) Answer the following.
a) Explain chemical coordination in humans and give the name and functions of some hormones.
Ans:
- In human coordination occurs in two ways which are the nervous coordination and the chemical coordination mostly.
- As hormones are the organic chemical produced by the various glands in the body hence coordination by the hormones is called as chemical coordination. And main thing is that horomones are secreted by the ductless glands which are directly released into the bloodstream through which they reach and react to their target organs.
- Endocrine system and nervous system works with each other in association to control and coordinate our body.
- Due to the environmental changes outside and inside the body hormones are secreted and which control and coordinate our body.
- Hormones are produced in small quantity by various glands but effective at lower concentrations.
- If there is abnormal secretion of hormones then it will cause the negative changes in our body which may dangerous.
Following are the hormones with their function.
- Pituitary gland is the master gland as it secrets growth hormone and also other hormones which regulate the secretion of other endocrine glands.
- The hormones secreted by pituitary gland with their functions are as follows.
- Prolactin : It is responsible for growth of mammary glands and formation of milk.
- TSH: It is responsible for synthesis and release of thyroid hormone.
- ACTH: It is responsible for stimulation of synthesis and secretion of steroid hormones.
- Vasopressin : It is called as anti-diuretic hormone as it prevents loss of water through urine.
- Thyroid gland secrets the hormone thyroxin which has following functions.
- It control working of kidney and also urine formation.
- It controls BMR.
- It helps in regulating the physical, mental and sexual growth of human body.
- It helps in regulating the growth of CNS and bones.
b) Explain the difference between excretory system of human and plants.
Ans:
Human excretory system:
- In animals there is special structure for excretion called as nephron which are the structural and functional unit of kidney.
- Kidney, lungs, skin are the excretory organs in human body through which wastes are expelled and helps in maintaining body.
- In animals waste is formed in the form of nitrogenous waste like urea, uric acid and ammonia and which excreted through human excretory system.
Excretory system in plants:
- In plants there is no special structure for excretion but they excrete the waste which are necessary to human beings.
- In plants through stomata and lenticels process of excretion is occured.
- In plants waste is formed in the form of CO2 and O2 only during photosynthesis which is the main thing of living organisms to survive.
- c) Explain coordination in plants with suitable example.
Ans:
In plants there is no nervous system to control and coordinate the stimulus but there will be tropic movement in response to the external stimulus which are explained in detail as below.
Phototropism:
- In this the growth movement of plant in response to light stimulus takes place.
- For example: In sunflower we can see Phototropic movement.
Geotropism:
- In this the growth movement of plant in response to force of gravity takes place.
- In geotropism we can see that roots of plant grows always in downward direction while shoots opposite to the direction of gravity.
Chemotropism:
- In this the growth movement of plants in response to chemical stimulus takes place.
- For example: the growth of pollen tube towards the ovule in the ovary.
Hydrotropism:
- In this the growth movement of plants in response to water takes place.
- For example: in some plants roots grows in the direction of water available.
Thigmotropism:
In this the growth movement of plants in response to touch or contact with solid object takes place.
7.) Explain in your own words with suitable example.
- a) what is meant by coordination.
Ans:
- Coordination is the process in which various organs works together in order to produce appropriate reaction to the given stimulus so that our body can react exactly and correctly to that response is called as coordination.
- In human coordination is takes place by nervous system and endocrine system.
- While in plants the coordination is takes place in response to external stimulus like phototropism, hydrotropism, geotropism etc.
b) How does excretion occurs in human beings.
Ans:
- Excretion is the process in which waste materials are removed from the body. In human excretion occurs through organs like lungs, kidney and skin. From lungs CO2 is removed as waste while through skin sweat is removed as waste and which maintains the body temperature.
- The main excretory organ on human is the urinary system which has kidney to filter the blood and forms the urine, nephrons are the structural and functional units of kidney.
- The following figure shows the human excretory system which consist of a pair of kidney, a pair of ureter and a urinary bladder, urethra.
- The urine formed in the kidney reach the urinary bladder through pair of ureter. And inside the urinary bladder the urine is stored till it is excreted.
- In kidney there are large number of filters called as nephron which is the structural and functional unit of kidney.
- When blood is passed through the tube the substances like glucose, amino acids, salt and water are get selectively reabsorbed. And finally remaining filtrate is collected in collecting tubule and enters the ureter.
Other than human excretory system some excretory organs are there which are discussed below.
- Lungs: It removes CO2 and water as waste.
- Liver: It removes the bile pigments such as vitamins, cholesterol, and the drugs along with the digestive waste.
- Skin: Skin and also the sebaceous glands present on the skin removes the substance such as sterols, hydrocarbons and wax sebum etc. And maintain the body temperature in every situation.
c) How is excretion in plants is useful to human beings.
Ans:
- In the process of photosynthesis plants remove oxygen as a by-product which is responsible for human life on the earth.
- Also in plants tannin is the waste product which is stored in the leaves and bark which is used in making tea in all the world.
- Some oils which are necessary for human are removed as a waste from plants and stored in their leaves.
d) Describe the transportation system in plants.
Ans:
- In plants the transportation system stores energy and supplies to all parts of plant. The raw material absorbed by the roots are also supplied to all parts of the plant through transportation system.
- Xylem tissue conducts the water minerals which are absorbed from the soil and supplies to all part of plant.
- While phloem transport the food materials from leaves to all parts of plant body.
Transportation of water in plants:
- Initially the water is absorbed through roots of the plants and it is supplied to all parts of plant body. Root pressure is responsible for the transportation of water in plants.
- While the most of the water is transported through transportation pull. And it is for the loss of water taken by plants and this loss occurs through stomata of the plants.
- When water is removed through stomata in atmosphere the water level in epidermal layer is decreases which is again maintained by absorbing water.
- And this loss is again covered by taking water to the leaves through xylem.
- Transpiration helps in the absorption of water and minerals to all parts of plant body and maintain the growth of plant body.
Transportation of food in plants:
- In plants transportation of food from leaves to all plant body occurs through vascular tissue and phloem and the process is called as translocation.
- Phloem consist of companion cells, sieve tubes, phloem parenchyma and fibres.
- Translocation in phloem is achieved by using energy from ATP.
- For example: When sucrose is transported through phloem tissue using ATP energy due to which osmotic pressure in the tissue increases and causes the water to move into it.
- Due to this pressure the material moves to the tissue having less pressure and helps in moving the material in plant body according to plant requirement.
- In this way, transportation of food in plants takes place.