Cls 7 Sci Chp 1 PPT and Notes

   CLASS 7 SCIENCE PPT    

    CHAPTER 1 NUTRITION IN PLANTS      

 

     Class 7 Science Notes  

   Chapter 1 Nutrition in Plants   

Nutrients:The components of food like carbohydrates, fats, proteins vitamins and minerals are called nutrients.Nutrients help living organisms :-★ To build their bodies.★ To grow.★ To repair the damaged parts of their bodies.★ To provide energy to carry out life processes. 

Nutrition :-The mode of taking food by an organism and its utilization in the body is called nutrition.Modes of nutrition :- There are two main modes of nutrition in living organisms. They are autotrophic nutrition and heterotrophic nutrition.Autotrophic nutrition :- is nutrition in which organisms can prepare their own food.Organisms which can prepare their own food are called autotrophs. Ex: PlantsHeterotrophic nutrition :- is nutrition in which organisms get their food directly or indirectly from plants.Organisms which get their food directly or indirectly from plants are called heterotrophs. Ex: Animals

Photosynthesis 

Food making process in plants :-

Photosynthesis is the process by which plants prepare their on food by using sunlight, water, carbon dioxide and chlorophyll.Photosynthesis take place in the leaves.★ Sunlight is obtained from the sun.★ Water is absorbed by the roots and transported to the leaves.★ Carbon dioxide is taken from the air through small pores in theleaves called stomata.★ Chlorophyll are the green pigments present in the leaves.

Chlorophyll uses the energy from sunlight to prepare food by using water and carbon dioxide. The food prepared is carbohydrate which is then converted into starch. During photosynthesis oxygen is released.Equation of photosynthesis :-                         sunlight6CO₂ + 6H₂O      →      C₆H₁₂O₆ + 6O₂                        Chlorophyl

cells  

★ Cells are the most basic unit of living organisms. 

★ Bodies of living organisms are made up of tiny units called cells. 

Stomata

★ There are tiny pores present on the surface of leaves which are surrounded by           guard cells. 

★ The exchange of gases (O₂ and CO₂) takes place through these pores. 

Synthesis of proteins :-
The soil has some bacteria which convert nitrogen from the air into usable nitrogen in the soil. Farmers also add fertilisers containig nitrogen into the soil. Plants absorb this nitrogen from the soil along with water and other constituents to prepare proteins and fats.

Heterotrophic Nutrition 

 In this type nutrition, organisms derive energy from plants and animal sources. 

★ Herbivores: The heterotrophs that derive their energy directly from plants are called herbivores. 

★ Carnivores: Those who derive their energy indirectly by eating herbivores are called carnivores. 

★ Omnivores: They feed on both plants and animals. Example: bear, rat, man etc. 

★ Decomposers: They obtain nutrients by breaking down remains of dead plants and animals, includes some bacteria and fungi. 

Other modes of nutrition in plants :-
Parasitic plants :- are plants which do not have chlorophyll and cannot prepare their own food. They get their food from other plants called host . Eg :- Cuscuta (Amarbel)

Insectivorous plants :- are plants which feed on insects. Eg:- Pitcher plant. The leaf of the pitcher plant is modified into a pitcher. The end of the pitcher has a lid which can open and close. When an insect enters the pitcher, the lid closes. The insect is then digested by digestive juices inside the pitcher.

Saprotrophs :- are plants which do not have chlorophyll and cannot prepare their on food. They get their food from dead and decaying organic matter. 

Eg :- mushroom, bread mould etc. They produce digestive juice on the dead and decaying organic matter and convert it into a solution and then absorb the nutrients from the solution.

Symbiotic relationship :- Some plants live together and share shelter and nutrients. 

Eg :- lichens. In lichens, an alga and a fungus live together. The fungus provides shelter, water and minerals to the alga. The alga provides food to the fungus which it prepares by photosynthesis.

How nutrients are replenished in the soil :-
Plants absorb nutrients from the soil. So the nutrients in the soil decreases. So farmers add manures and fertilisers to the soil to increase the nutrients in the soil. The bacterium called rhizobium which lives in the roots of leguminous plants like grams, peas, beans etc. converts nitrogen from the air into soluble form in the soil and makes the soil rich in nitrogen. In return the plant provides food and shelter to the bacteria. So they have a symbiotic relationship.
👉NCERT Solutions of Nutrition in plants Class 7

Cls 10 Chp 8 solsn

 

Class 10 Science 

Chapter 8 How Do Organisms Reproduce?

Intext Question and Answer      

Page Number: 128        

1. What is the importance of DNA copying in reproduction?

Ans:

DNA copying has following importance in reproduction:

• It maintains the characteristics of species.
• It maintains the continuity of life.
• From this, the characteristics and features of organisms are transformed to their progeny.
• It produces variations in organisms which is the basis of evolution of new species.

2. Why is variation beneficial to the species but not necessarily for the individual?

Ans:

The various populations of organisms interact with many types of ecological niches. This is important for them to survive in given conditions. In case of any damage caused to the ecological conditions of the population, the population gets adversely affected. The organisms which are able to survive, may reproduce to develop population which is adapted or suited to the varied conditions. Hence variation is beneficial to species, but not to the individuals.

Page Number: 133        

1. How is the process of pollination different from fertilisation?

Ans:

★ When a single cell divides into two equal halves, it is known as binary fission. Bacteria and amoeba are examples of binary fission.

★ When a single cell divides into multiple daughter cells at the same time, it is known as multiple fission. Algae and sporozoans are examples of multiple fission.

2. How will an organism be benefited if it reproduces through spores ?

Ans: An organism is benefited by reproducing through the spores because spores are surrounded by a thick layer which protects them in adverse conditions. When the favourable conditions occur, these spores start to grow again. In this way they are successfully live in unfavourable conditions.

3. Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration ?

Ans: In complex multicellular organisms, specialised cells make up tissues, tissue make up organs, organs make up organ systems and finally organ systems make up organisms. Since complex multicellular organisms have a very high degree of organisation in their body, they cannot be reproduced from their cut body parts by the process of regeneration.

4. Why is vegetative propagation practised for growing some types of plants?
Ans: Vegetative propagation is practiced for growing such plants which usually do not produce seeds or produce non-viable seeds.

5. Why is DNA copying an essential part of the process of reproduction?
Ans:
★DNA copying is essential part of the process of reproduction so that the characteristics of the parent organisms are transmitted to its offspring and at the same time some occasional variations are also produced in the offspring. 

★ The changes in the copy of DNA provide an organism the capability to survive in changing conditions.

Page Number: 140           

1. How is the process of pollination different from fertilisation?

Ans:

Pollination	Fertilisation
1. The transfer of pollen grains from the anther of a stamen to the stigma of a carpel is called pollination.	1. Fertilisation occurs when the male gamete present in pollen grain joins with the female gamete (or egg) present in ovule.
2. It takes place by various pollinating agents.	2. It takes place by natural or artificial means.

2. What is the role of the seminal vesicles and the prostate gland ?
Ans:

They add their secretion to make the sperm transport easier and provide nutrition.

3. What are the changes seen in girls at the time of puberty?

Ans : The various changes occur in girls at puberty are :

★ Hair grow under armpits and pubic region.

★ Mammary glands (or breasts) develop and enlarge.

★  The hips broaden.

★ Extra fat is deposited in various parts of the body like hips and thighs.

★ Fallopian tube, uterus and vagina enlarge.

★ Ovaries start to release eggs. g. Menstruation (monthly periods) starts.

★ Feelings and sexual drives associated with adulthood begin to develop.

4. How does the embryo get nourishment inside the mother’s body ?

Ans:

★The embryo gets nourishment inside the mother body through a special tissue called placenta. 

★It provides a large surface area for the transfer of glucose, oxygen and other substances from the mother to the embryo.

5. A woman is using a copper-T. Will it help in protecting her from sexually transmitted diseases ?

Ans:

 It cannot prevent a women from sexually transmitted diseases. These diseases are transmitted by contact which cannot be prevented by copper-T.

Exercise Questions        

1. Asexual reproduction takes place through budding in

(a) amoeba                    (b) yeast      

(c) plasmodium            (d) leishmania

Ans: (b) Yeast

 2. Which of the following is not a part of the female reproductive system in human beings ?
(a) Ovary                  (b) Uterus
(c) Vas deferens       (d) Fallopian tube
Ans: (c) Vas deferens

3. The anther contains
(a) sepals      (b) ovules
(c) carpel      (d) pollen grains
Ans:   (d) Pollen grains

4. What are the advantages of sexual reproduction over asexual reproduction?

Ans:

Following are the advantages of sexual reproduction:

• The offspring has the characters of both the parents.
• The survival of the species is ensured as there are more variations.
• The offspring can easily adapt to environmental changes.
• It also improves the health of humans.

5. What are the functions performed by the testis in human beings ?

Ans: 

They are responsible for producing the male sex hormone, testosterone. They are responsible for producing sperms 

6. Why does menstruation occur ? (Sep 2020)

Ans. : 

★ The uterus prepares itself every month to receive a fertilized egg and thus its lining becomes thick and spongy.

★ If the egg is not fertilized, the lining slowly breaks and comes out through the vagina as blood and mucous.

7. Draw a labelled diagram of the longitudinal section of a flower.
Ans:

8. What are the different methods of contraception?

Ans:

The different methods of contraception are as follow :

(i) Barrier method : In this method, condom, diaphragm and cervical caps are used. These prevent the entry of sperms in the female genital tract during sexual intercourse.

(ii) Chemical method : In this method a woman uses two kinds of pills (oral and vaginal pills). The oral pills are hormonal preparations which suppress the release of ovum in fallopian tube. These are called oral contraceptives. The vaginal pills/ creams are spermicidal. The chemicals in these spermicidals kill the sperms during their journey in the vaginal tract.

(iii) Intrauterine contraceptive devices : Intrauterine contraceptive devices such as copper-T are placed safely in the uterus by a skilled doctor. It prevents the sperms to reach the uterus.

(iv) Surgical method : In this method, a small part of vas deferens of male and fallopian tube of female is cut or tied by surgery. It is called vasectomy in males and tubectomy in females.

9. How are the modes for reproduction different in unicellular and multicellular organisms?
Ans:

Reproduction mode in unicellular organisms	Reproduction mode in multicellular organisms
(i) A sexual reproduction takes place in unicellular organisms.	(i) Sexual reproduction takes place in multicellular organisms.
(ii) Only one organism is required in this method.	(ii) A male and a female both are required in this method.
(iii) No special cells are present for reproduction.	(iii) Special cells are present for reproduction.
(iv) No special organs are present for reproduction.	(iv) Special organs are present for reproduction located at the fixed position in the body.

10. How does reproduction help in providing stability to populations of species?

Ans:

The introduction of variations during reproduction provides stability to the populations of various species by preventing them from getting wiped out during adverse conditions. Reproduction also helps to generate copies of individuals which are suited to a particular environment.

11. What could be the reasons for adopting contraceptive methods?

Ans:

The reasons for adopting contraceptive devices are as follow:

1. To control the birth rate and prevent the increase in population.
2. To reduce the adverse effects on mother’s body due to frequent pregnancy.
3. To provide safety from sexually transmitted diseases.

cls 10 chp 7 solsn

Class 10 Science Solution
     Chapter 7 Control and Coordination      

 Intext Question and Answer      

Page Number: 119        

1. What is the difference between a reflex action and walking?
Ans:

Reflex action	Walking
1. It is the action which is performed automatically.	1. It is a response to the information transmitted by nerve to muscles of the legs. In this case, thinking is involved.
2. It is controlled and coordinated by spinal cord.	2. Brain instructs and controls leg muscles to move.
3. It is an involuntary action.	3. It is a voluntary action.

2. What happens at the synapse between two neurons?

Ans:

The small empty space between two nerve cells is called synapse. At synapse, a chemical substance is produced at the end of axon of one nerve cell that reaches to the other nerve cell through the dendrite.

3. Which part of the brain maintains posture and equilibrium of the body ?
Ans:
Posture and equilibrium of the body are controlled by cerebellum.

4. How do we detect the smell of an agarbatti (incense stick) ?
Ans:

★ The smell of agarbatti (incense stick) diffuses in the air.

★ It is detected by olfactory receptors present in the nose.

★ This information is sent to olfactory lobe by sensory nerves located in the forebrain.

★ It responds to the information.

5. What is the role of the brain in reflex action ?

Ans:

There is no role of brain in reflex action. These involuntary actions are controlled by the spinal cord which take place immediately without thinking of how to respond to the stimuli.

Page Number: 122          

1. What are plant hormones ?
Ans:
Plant hormones are also called phytohormones. Plant hormones are the chemical substances which help in controlling growth, flowering, height, development of plants and their response to the environment.

2. How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light ?
Ans:

Movement of leaves of sensitive plant	Movement of a shoot towards light
1. It is a nastic movement which does not depend on the direction of stimulus applied.	1. It is a tropic movement which depends on the direction of stimulus applied.
2. The stimulus is touch.	2. The stimulus is light.
3. It is caused by the sudden loss of water from the swellings at the base of leaves.	3. It is caused by the unequal growth on the two sides of the shoot.
4. It is not a growth movement.	4. It is a growth movement.

3. Give an example of a plant hormone that promotes growth.                                

Ans:                                                                                                                               

Auxin.

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

Ans:                                                                                                                                  

When a tendril comes in contact with a support, auxin stimulates faster growth of the cells on the opposite side that's why the tendril forms a coil around the support.

5. Design an experiment to demonstrate hydrotropism.

Ans:

Take two glass troughs A and B and fill each one of them two-thirds with soil. In trough A plant a tiny seedling. In trough B plant a similar seedling and place a c/ay pot inside the soil. Water the soil in trough A daily and uniformly. Do not water the soil in trough B but put some water in the clay pot. Leave both the troughs for a few days.

Page number 125         

1. How does chemical coordination take place in animals?

Ans:

★ Chemical coordination takes place in animals with the help of chemical messengers called hormones. 

★ Hormones are the chemicals that are secreted by specific endocrine glands. Hormones regulate the growth, development and homeostasis of the animals.

 2. Why is the use of iodised salt advisable ?
Ans:
★ It is advised to use iodised salt because thyroid gland needs iodine to produce thyroxin hormone. 

★ Thyroxin hormone controls all the metabolic activities of our body like metabolism of carbohydrates, fats and protein etc. 

★ Due to the deficiency of thyroxin a disease called goitre is caused.

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

Ans: 

★ Adrenaline is directly secreted into the blood. The blood to the skin is reduced due to contraction of muscles around small arteries.

★The breathing rate increases because of the contractions of the diaphragm and the rib muscles. The heart beats faster, resulting in supply of more oxygen to the muscles.

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

Ans :

★ Insulin hormone regulates blood sugar levels.

★ To treat increased level of blood sugar, the diabetic patients are treated by giving injections of insulin.

Exercise Questions        

1. Which of the following is a plant hormone?
(a) Insulin            (b) Thyroxin
(c) Oestrogen       (d) Cytokinin
Ans:    (d) Cytokinin

2. The gap between two neurons is called a
(a) dendrite      (b) synapse
(c) axon            (d) impulse
Ans:  (b) Synapse

3. The brain is responsible for
(a) thinking
(b) regulating the heart beat
(c) balancing the body
(d) all of the above
Ans: (b) All of the above

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 ? 

Ans:

(i) Phonoreceptors are found in Ear. Their function is to hear and balance of the body.

(ii) Photoreceptors are found in Eyes. Their function is to see.

(iii) Olfactory receptors are found in Nose. Their function is smell detection.

(iv) Thermoreceptors found in Skin.- Its function is to feel the heat, cold or touch.

(v) Gustatory receptors found in Tongue - Its function is to detect Taste.

When receptors do not work properly, the environmental stimuli are not able to create nerve impulses and body does not respond.

5. Draw the structure of a neuron and explain its function.
Ans:
Nerve cell or neuron is the functional unit of nervous system. A nerve cell has three parts-
(i) cell body
(ii) dendrite
(iii) axon

Function : 

★ The function of nerve cells is to carry information in the form of electrical signals which are called nerve impulses. 

★ Cells receive stimulus to send it to spinal cord and brain and carry the message from brain to the target organ.

6. How does phototropism occur in plants ?
Ans:
★ Phototropism in plants occurs due to the hormone auxin. 

★ When light falls on one side of a plant, the secretion of auxin hormone is more in the part away from the light. 

★ Hence, auxin causes growth in length of the cells in shady part. So, the plant appears to bend towards light.

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

Ans:

★ All the involuntary actions will get disturbed.

★ Reflex actions will be disturbed because reflexes are located in the spinal cord. Therefore, the quick responses required to safe guard the body will not take place.

8. How does chemical coordination occur in plants ?

Ans:

Chemical coordination in plants takes place with the help of plant hormones. In most of the regions where division takes place (meristematic regions) stimuli cells secrete chemical compounds (hormone). These substances identify the information by stimulating the other nearby cells and communicating the information.

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

Ans:

An organism needs control and coordination system for the following functions :

★  To save the body of the organisms from the harmful changes in the environment.

★  To control the speed of voluntary and involuntary actions.

★  To have the capability to think and learn for responding to any stimuli.

10. How are involuntary actions and reflex actions different from each other ?
Ans:

Involuntary actions	Reflex actions
1. Those actions which occur immediately without any thinking are called involuntary actions.	1. Reflex action is an immediate response to an event which does not require any processing by brain.
2. Involuntary actions are controlled by mid and hind brain. Example: Breathing, beating of heart, etc.	2. Reflex actions are controlled by spinal cord. Example: Sneezing, coughing, etc.

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

Ans:

Nervous mechanism	Hormonal mechanism
It is a fast process.	It is a slow process.
Arteries and glands are affected.	It affects the target organ.
It transmits in electrochemical form.	It transmits in chemical form.
It does not control metabolism.	It controls metabolism.
Growth is not affected.	Growth is affected.

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

Movement in a sensitive (mimosa) plant	Movement in legs of a human
1. The leaves of a sensitive plant like mimosa are sensitive to touch.	1. Leg is in control of nerve muscles.
2. It is not controlled by any part of the plant.	2. It is controlled by brain and spinal cord.
3. In this, cells change their shape on changing the amount of water in them.	3. Amount of water has no effect on the movement of muscles.
changing the amount of water in them.	the movement of muscles.
4. The movement in a sensitive plant are nastic movement.	4. The movement in our leg is due to voluntary nervous system.

Click below to join👇