Holozoic Heterotrophic Nutrition Nutrition in Animals Modes of Nutrition Photosynthesis Factors affecting Photosynthesis (Activities) Amoeba Humans Types of Respiration Anaerobic Aerobic
Respiratory System of Man Diffusion
Autotrophic
Saprophytic
Parasitic
Respiration
Respiration in Plants and Animals
Transportation
Internal Structure of Heart Exchange of Gases Blood Vessels Blood Platelets Lymph
Transportation in Plants
Transport of Water Transport of Food and Other Substances Excretion
Excretion in Human Beings Excretion in Plants Structure of Nephron
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Life Processes:
Movement of various types can be taken as indication of life.
Definition:
Life processes can be defined as the processes which together perform various functions of the body.
Criteria to identify living organisms:
Breathing, Respiration, movement of animals.
Growth of the plants.
Molecular movements as seen in cells of the body of animals and plants
Importance of Life Processes:
The maintenance of life requires processes like nutrition, respiration, transport of materials within the body and excretion of waste products
Nutrition:
For every individual to grow nutrient is must which is completed by nutrition.
Nutrition is the intake and utilization of substances that are necessary for growth, energy, maintenance and activities of the plants or animals.
Respiration:
Simple molecules obtained after digestion need to be broken down by chemical reactions like oxidation and reduction.
Breakdown of this molecules release tremendous amount of energy required to carry out various function in our body.
Respiration can be defined as biochemical process which involves the intake of oxygen from outside the body and use it in the process of break down of food sources for cellular needs.
Transportation:
Whatever food and oxygen is taken by the organism has to be transported to all the parts of the body. Thus this is possible by the process of transportation, with the help of circulatory system.
Excretion:
The metabolic activities going in our body creates many byproducts or waste products (nitrogenous waste) which has to be eliminated from the body otherwise it may turn into toxic and be harmful to body.
So the process of excretion is necessary for removal of waste products from the body. It is carried out by the excretory system.
Diffusion:
Simple diffusion can be seen in unicellular organisms where the body is in direct contact with the environment. They do not need special organs for intake of food, exchange of gases or removal of wastes.
In multicellular organisms the body is not in direct contact with the environment so simple diffusion is not possible and cannot meet the oxygen requirements of all the cells.
Nutrition:
Nutrition is defined as the procurement and utilization of substances that are necessary for growth, energy, maintenance and activities of the plant or animals or in other words, it is the process of intake, as well as utilization of nutrients by an organism.
The chemical substances that provide nourishment (as energy source or for biosynthesis of body constituents) to living organisms are called nutrients.
Nutrients may be:
Simple organic molecules Complex organic molecules Inorganic or mineral ions
Modes of Nutrition:
Basically, there are two modes of nutrition i.e. autotrophic and heterotrophic nutrition
Autotrophic Nutrition:
The process mainly occurs in green plants and some forms of bacteria.
The mode of nutrition in which an organism builds up its own organic food from inorganic substances is known as autotrophic nutrition.
The organisms showing autotrophic nutrition are called autotrophs.
The autotrophs synthesise their food either by the process of photosynthesis or by chemosynthesis.
Carbohydrates are utilised for providing energy to the plants. In plants the carbohydrates which are not used are stored in form of starch which serves as the internal energy reserve.
In human body the energy derived from the food is stored in the form of glycogen.
Photosynthesis:
Plants prepare food in the form of carbohydrates and proteins by the process of photosynthesis.
Photosynthesis literally means, “to put together by light”.
Photosynthesis means synthesis of organic matter by the autotrophs (phototrophs) in the presence of light, using chlorophyll, CO2 and H2O.
Photosynthesis is the only process by which the solar energy is trapped by the producers and converted to food energy for all the organisms.
It is the only natural process in which CO2 is consumed and oxygen is liberated.
The overall equation of photosynthesis is, Nutrition
Heterotrophic Autotrophic
Saprophytic (e.g. yeast, moulds, mushrooms)
Holozoic (e.g. amoeba, frog, human being) Parasitic (e.g. cuscuta, tape worms, orchids, lice, round worms, leeches and ticks) Phototrophic (Eg. Plants)
80 Universal Tutorials – X CBSE (2012–13) – Biology Volume 6CO2 + 6H2O l chlorophyl sunlight → C6H12O6(glucose) + 6O2 OR 6CO2 + 12H2O l chlorophyl sunlight → C6H12O6(glucose) + 6H2O + 6O2
Events occurring during Photosynthesis:
Absorption of light energy by chlorophyll.
Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen (light reaction and photolysis of water).
Reduction of CO2 to carbohydrates (Dark reaction or Calvin Cycle).
All the above events do not occur in sequence for e g. In desert plants they take up CO2 at night and prepare an intermediate which is acted upon by the energy absorbed by the chlorophyll during the day.
Chloroplast – The Site of Photosynthesis:
Plant cells have chloroplast, (an organelle) which contain chlorophyll.
The green colour of the plants is due to presence of pigment chlorophyll.
Chlorophyll is a photosynthetic pigment.
Raw Materials During Photosynthesis:
1) Carbon dioxide and Water: The synthesis of carbohydrates requires two substances i.e. carbon dioxide and water.
The plants use carbon dioxide, which is present in atmosphere and is released during respiration. It enters into the plant leaf through specialized pores called stomata.
The aquatic plants use carbon dioxide dissolved in water.
Water required for photosynthesis is absorbed by roots from the soil through osmosis.
Water moves up through the xylem to the leaves and ultimately to photosynthesizing cells.
2) Other materials:
It includes nitrogen, phosphorus, iron and magnesium.
Nitrogen is used for photosynthesis of proteins and other compounds.
This is taken up in the form of inorganic nitrates and nitrites.
It is also taken up in the form of organic compounds prepared by bacteria from atmospheric nitrogen.
Factors Affecting Photosynthesis:
The various factors influencing the rate of photosynthesis (and hence productivity) are as follows:
Light Intensity:
In the absence of light of sufficient intensity, the plants do not photosynthesize. Instead, they take in oxygen and release carbon dioxide i.e. they respire.
The rate of photosynthesis increases at the lower intensities of light and decreases at higher intensities.
Availability of Carbondioxide:
The rate of photosynthesis increases with increase in CO2 content. But after a certain limit, there is no effect of CO2 concentration on photosynthesis and further increase can be inhibitory.
CO2 is a limiting factor in photosynthesis on clear summer days when plants are provided with adequate water.
In land plants, the CO2 enters the leaf through stomata. Hence when the stomata are closed, rate of photosynthesis is zero.
Stomata:
Exchange of gases occurs across the surface of stems, roots and leaves by specialize structures called as stomata.
Stomata are small pores present on upper (monocots) and lower (dicots) surface of leaf.
The opening and closing of the pore is a function of the guard cells.
Guard cells swell when water enters inside and stomatal pore opens.
When the guard cells shrink the pore closes.
Heterotrophic Nutrition:
The mode of nutrition in which the organisms obtain water, minerals or certain organic compounds from other organisms, i.e. the autotrophs, is known as heterotrophic nutrition.
Mostly animals, bacteria and fungi show heterotrophic nutrition. The organisms showing heterotrophic nutrition are called heterotrophs.
In this mode of nutrition, complex molecules are digested into simpler forms, which are then utilized by organisms.
Heterotrophic nutrition is of different types i.e. saprophytic, parasitic and holozoic nutrition. Saprophytic (Saprozoic) Nutrition:
In this mode of nutrition, organisms grow and live on dead or decaying organic matter including animal and plant remains. They break down the food material outside the body and then absorb it.
Parasitic Nutrition:
In this mode of nutrition, the organism (parasite) depends upon other organism (host) for its nutritional requirements. They derive nutrition from plants or animals without killing them.
Holozoic Nutrition:
All vertebrates and many invertebrates eat whole plants, whole animals or their parts. So mode of nutrition in which complex organic matter from plants or animals is ingested, digested and absorbed is called holozoic nutrition.
(a) (b)
(a) Open and (b) closed stomatal pore
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Nutrition in Animals:
In unicellular organisms the food is taken in by the entire surface.
Eg. Paramoecium has a definite shape and food is taken in at a specific spot.
Food is moved to this spot by the movement of cilia which cover the entire surface of the cell. In multicellular organisms they have specific system called as digestive system to perform the
process of nutrition / digestion.
Nutrition in Amoeba:
The food of Amoeba consists of planktonic (that float on water body) microscopic plants and animals.
Its mode of nutrition is holozoic.
Amoeba obtains its food by a process called phagocytosis. Amoeba engulfs the food with the help of pseudopodia.
When the food is completely encircled, tips of pseudopodia touch each other. The membrane at that point dissolves and the food is stored in food vacuole.
Amoeba shows intracellular digestion.
Lysosomes containing digestive enzymes fuse with the food vacuole to form the digestive vacuole.
The enzymes break the larger molecules into smaller molecules (digestion).
The membrane of the vacuoles is drawn into fine canals, which transfer the products of digestion into the cytoplasm (absorption). In the cytoplasm, the food is utilized by the cell (assimilation) The undigested matter is thrown out of the cell by exocytosis
(egestion).
Human digestive system:
Alimentary canal is 9 m long extending from mouth to anus.
Mouth:
Mouth is the front opening of alimentary canal bounded by two sensitive lips. Mouth opens into buccal cavity.
Buccal Cavity
Buccal cavity is provided with 4 types of teeth for cutting, tearing, chewing and grinding the food.
Muscular tongue is present at the floor of buccal cavity which bears taste buds and acts as a sense organ for taste.
Tongue helps in pushing the food to pharynx.
Salivary Glands:
When the food is taken in the mouth it is made soft by Saliva secreted by salivary glands in the mouth. Saliva contains an enzyme called salivary amylase which converts starch into sugar. Thus digestion starts in buccal cavity
Oesophagus:
The food crushed in the mouth is taken to the stomach by long muscular tube called oesophagus.
This is also called as gut which pushes the food to stomach by peristaltic movement. No digestion takes place here.
Stomach:
It is a large J–shaped organ present on the left side of the abdomen. The stomach wall has branched and tubular glands called gastric glands.
Gastric Glands:
They secrete gastric juice. Gastric juice is a mixture of three secretory products like HCl, Protein digesting enzyme (Pepsin) and mucus.
Functions:
Muscular walls of the stomach help in mixing the food thoroughly with more digestive juices (Churning of food).
Hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin.
HCl also kills the bacteria and makes the food disinfectant.
Pepsin breaks down proteins into peptones.
Mucus protects the inner lining of the stomach from the action of the acid under normal conditions.
Thus, when food reaches stomach it mixes with gastric juice and protein digestion starts in the stomach.
Small intestine:
Food from the stomach enters into small intestine regulated by sphincter muscles. Small intestine is the longest part which is fitted into compact space because of the coiling.
Human alimentary canal
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Complete digestion of fats, carbohydrates and proteins takes place in small intestine. Food coming from stomach to small intestine is acidic. This food is made alkaline with the help of secretions of liver and pancreas, so that it is easy for the action of pancreatic enzymes.
The secretion of liver and pancreas are poured in duodenum part of intestine.
Liver: It is present on the right side of the abdomen. Liver secretes bile which contains bile pigment and bile salts. Bile salt breaks the larger fat molecules into small globules and increases the efficiency of enzyme action (Emulsification of fats).
Pancreas: It is a large gland lying parallel to and beneath the stomach. It secretes digestive enzymes as well as the hormones (insulin and glucagon). Pancreas secretes pancreatic juice which contains enzymes like trypsin and lipase.
Trypsin digests proteins and Lipase helps in breaking down of emulsified fats.
Walls of small intestine also contain glands which releases intestinal enzymes for the complete digestion of food.
Final conversion done by Enzymes:
Proteins are converted to amino acids.
Carbohydrates are converted to glucose.
Fats are converted to fatty acids and glycerol.
Summary of digestion
Starch Salivary amylase / Ptyalin Simple sugar (Complex Sugar)
Proteins Pepsin Peptones
acidic medium
Lipids Bile salts Emulsified fats
(Large molecules) (Small fat globules)
Emulsified fats P. lipase fatty acids + glycerol
alkaline medium
Starch P. amylase Simple sugar (Complex Sugar) alkaline medium
Peptones P. trypsin Peptides
alkaline medium
Absorption of Small intestine:
Internally the walls of small intestine are provided by long finger like projections called as villi. Whose functions is
i) Increasing the surface area for absorption.
ii) Carry the absorbed food to each and every cell of the body as they are rich in blood vessels.
iii) The absorbed food in the form of simple molecules reaches the cells through blood stream and is utilized. Utilization of food means using it for building up new tissues, repair of old tissues and for obtaining energy.
Large intestine:
The unabsorbed food is sent to large intestine where more villi absorb water from this material.
Rectum:
The undigested food collects as faecal matter in the rectum.
Anus:
The waste material is thrown out from the body by anus regulated by anal sphincter.
Note:
Length of small intestine is different in various animals depending on the food they eat.
Herbivores have longer small intestine because they eat grass and the cellulose has to be digested. Carnivores have shorter small intestine because they eat meat which is digested easily.
APPENDIX:
Activity 6.1 :
Aim: Chlorophyll is necessary for photosynthesis
Steps Reasons / Observation
Take a potted plant with variegated leaves eg. Crotons
Keep it in dark room for 3 days To remove the starch Keep the plant in sunlight for about 6 hrs.
Pluck a leaf and mark green area in it and trace them on sheet of paper.
Dip the leaf in boiling water for few minutes To remove chlorophyll Place the leaf in boiling alcohol. What is the
colour of solution?
To decolorize the leaf. Colour of the solution will be green
Dip the leaf in iodine solution for few minutes To mark the areas of starch Remove the leaf and rinse off the iodine
solution
Observe the colour of the leaf and compare with tracing of the leaf done in the beginning
Portion of leaf having chlorophyll turns blue − black while non –green parts do not turn blue – black. In the earlier leaf it was colourless Conclusion / Inference:
Starch formation takes place in that part of the leaf which has chlorophyll. Starch is not formed in the absence of chlorophyll.
86 Universal Tutorials – X CBSE (2012–13) – Biology Volume
Activity 6.2:
Aim: CO2 is necessary for photosynthesis
Steps Observation / Reasons
Take two healthy potted plants of same size
Keep in dark room for 3 days To remove the starch from leaves Place each plant on separate glass plates.
Place a watch – glass containing potassium hydroxide by the side of one of the plants.
Potassium hydroxide is used to absorb carbondioxide
Cover both the plants with separate bell jars Vaseline should be used to seal the bottom of the jars to the glass plates.
To keep the set – up airtight
Keep the plants in sunlight for 2 hours
Pluck a leaf and check for presence of starch. Starch will be seen in bell jar ‘b’ Do both the leaves show the presence of the
same amount of starch?
No,
Conclusion:
Photosynthesis will occur in the presence of carbondioxide in bell jar ‘b’ and not in ‘a’. So carbondioxide is necessary for photosynthesis.
Activity 6.3:
Aim: To check the action of saliva on starch
Steps Observation / Reasons
Take 1 mL starch solution (1%) in two test tubes (A and B).
Add 1 mL saliva to test tube A and leave both test tubes undisturbed for 20-30 minutes.
Now add a few drops of dilute iodine solution to the test tubes.
To detect the broken down starch
In which test tube do you observe a colour change?
In test tube A
What does this indicate about the presence or absence of starch in the two test tubes?
Starch is broken down in test tube A and undigested in test tube B
What does this tell us about the action of saliva on starch?
The saliva contains an enzyme called salivary amylase that breaks down starch which is a complex molecule to give sugar.
(a) (b)
Experimental set-up (a) with potassium hydroxide (b) without potassium hydroxide
Bell jar Watch glass
containing potassium hydroxide
Respiration:
Organisms require energy to maintain various life processes.
The energy needed is obtained from the oxidation of simple organic compounds like glucose and for this a continuous supply of oxygen is needed.
Respiration is a biochemical process taking place in the mitochondria with the help of several enzymes.
The energy released in respiration is chemical energy which gets stored in adenosine triphosphate molecules (ATP).
Types of Respiration:
Depending upon the requirement of oxygen, the respiration is of two types i.e. aerobic and anaerobic respiration.
The first step is the break-down of glucose, (a six-carbon molecule) into a three-carbon molecule called pyruvate.
This process takes place in the cytoplasm, which is independent of oxygen. Further, the pyruvate may enter into aerobic and anaerobic respiration.
Aerobic Respiration:
It takes place in the presence of oxygen and food is oxidized completely.
It breaks down 3 carbon pyruvate molecules to give 3 molecules of CO2. Other product is H2O
Breakdown of pyruvate using oxygen takes place in the mitochondria with release of high energy.
It produces 38 ATP per molecule of glucose, e.g., body tissues of vertebrates. The high- energy bonds of ATP are subsequently broken down to use the energy for various activities.
It is commonly seen among higher plants and animals. Anaerobic Respiration:
Respiration occurring in the absence of O2 is called anaerobic respiration.
Since this process takes place in the absence of air (oxygen), it is called anaerobic respiration.
In one type of anaerobic respiration known as alcoholic fermentation, CO2 and ethanol are formed as byproducts. This process takes place in yeast during fermentation
In other type of anaerobic respiration known as lactic acid fermentation, the end product is lactic acid. This process takes place in lactic acid bacteria, skeletal muscles.
Comparatively less energy is released. It produces 2 ATP per molecule of glucose. For example- Yeast, lactic acid bacteria, intestinal parasites, liver flukes, skeletal muscles