Nutrition and types of nutrients
A mobile phone needs charging to work, and a car needs fuel to run. A child who skips lunch cannot play well in the afternoon. Every living thing needs food to get energy, grow and repair itself.
Nutrition (पोषण) is the process of taking in and using food. Substances that are digested and assimilated for energy, growth and health are foodstuffs.
In the figure : In the figure (a sketch with sample numbers) the macro-nutrients (carbohydrates, proteins and fats) are needed in large amounts, the micro-nutrients (minerals and vitamins) in small amounts.
Rule 1: Why we need nutrition — For energy, growth and development, replacing damaged cells and repairing tissues, and fighting diseases.
- Easy : Energy: for running and playing.
- Medium : Repair: a cut on the finger heals with the help of nutrients.
- Exam-type : Fighting diseases: a well-nourished child recovers faster.
Rule 2: Macro, micro; autotrophs and heterotrophs — Macro-nutrients (large amounts): carbohydrates, proteins, fats. Micro-nutrients (small amounts): minerals and vitamins. Autotrophic organisms make their own food; heterotrophic organisms depend on others.
- Easy : Rice is a carbohydrate (macro).
- Medium : Iron is a mineral (micro).
- Exam-type : A plant is autotrophic; a cow is heterotrophic.
Macro = carbohydrates, proteins, fats (more). Micro = minerals, vitamins (less).
Thinking micro-nutrients are less important because they are needed in small amounts. They are still essential.
Memory clue: Macro = Many (CPF), Micro = Meagre (MV).
Spot the difference
| Type | Amount needed | Examples |
|---|---|---|
| Macro-nutrients | Large | Carbohydrates, proteins, fats |
| Micro-nutrients | Small | Minerals, vitamins |
| Autotroph / heterotroph | Makes / depends | Plant / cow |
Practice questions
- 1What is nutrition?
- 2Why do organisms need nutrition?
- 3Name the macro-nutrients.
- 4Name the micro-nutrients.
- 5What are autotrophic organisms?
- 6What are heterotrophic organisms?
- 7Classify as autotroph or heterotroph: mango tree, tiger, mushroom, grass.
- 8Ravi says vitamins can be skipped as they are needed only in tiny amounts. Correct him.
Show answers (try them yourself first)
- 1The process of taking in and using food.
- 2For energy, growth, repair and to fight diseases.
- 3Carbohydrates, proteins and fats.
- 4Minerals and vitamins.
- 5Organisms that make their own food.
- 6Organisms that depend on others for food.
- 7Autotroph: mango tree, grass. Heterotroph: tiger, mushroom.
- 8Micro-nutrients are needed in small amounts but are still essential for health.
Photosynthesis and transport in plants
A plant kept in a dark cupboard turns pale and weak, but in sunlight it is green and strong. The green leaves are small kitchens in which the plant cooks its food using sunlight.
Photosynthesis (प्रकाशसंश्लेषण) is the process in which plants make food from water, minerals and carbon dioxide using sunlight and chlorophyll. Xylem (जलवाहिनी) carries water and minerals; phloem (अन्नवाहिनी) carries food.
In the figure : In the figure of photosynthesis A is sunlight, B carbon dioxide (through the stomata) and D water from the roots; they go in. C oxygen is released and E food (glucose) is made.
Photosynthesis and transport in plants
In the app you can move this figure with your finger.
Open in the appRule 1: Equation — 6CO2 + 6H2O → C6H12O6 + 6O2. Light energy is changed to chemical energy and oxygen is released. CO2 enters through the stomata; green stems also photosynthesise.
- Easy : For 1 glucose: 6 CO2 and 6 H2O are used.
- Medium : For 2 glucose: 2 × 6 = 12 CO2 are used and 2 × 6 = 12 O2 are released.
- Exam-type : Check: carbon on the left 6 × 1 = 6 and on the right 6 × 1 (in glucose) = 6, so the equation is balanced for carbon.
In the figure : In the figure A is the xylem, which carries water and minerals up from the roots. B is the phloem, which carries food down from the leaves to the other parts.
In the figure : In the figure a stem kept in red water: the red water rises through the xylem (A). The phloem (B) is next to it.
Photosynthesis and transport in plants
In the app you can move this figure with your finger.
Open in the appRule 2: Xylem and phloem — Xylem carries water and minerals from roots to the aerial parts. Phloem carries food (glucose) from leaves to other parts.
- Easy : Xylem: up from roots.
- Medium : Phloem: food from leaves to the rest.
- Exam-type : In a stem kept in red water, the red colour shows the path of xylem.
Photosynthesis needs sunlight, chlorophyll, water, minerals, CO2; gives glucose and O2. Xylem: water up. Phloem: food around.
Mixing up xylem and phloem. Xylem = water; Phloem = food.
Memory clue: Xylem → water; Phloem → food (P = plate).
Spot the difference
| Tissue | Carries | Direction |
|---|---|---|
| Xylem | Water and minerals | Roots to aerial parts |
| Phloem | Food (glucose) | Leaves to other parts |
| Stomata | CO2 enters | Into the leaf |
Practice questions
- 1What is photosynthesis?
- 2Write the equation of photosynthesis.
- 3Through which parts does CO2 enter a leaf?
- 4Which gas is released in photosynthesis?
- 5What does the xylem carry?
- 6What does the phloem carry?
- 7How many CO2 molecules are needed to make 3 glucose molecules?
- 8A white flower is kept in red water and its veins turn red. Name the tissue that carried the colour and tell its function.
Show answers (try them yourself first)
- 1The process in which plants make food using sunlight, chlorophyll, water and CO2.
- 26CO2 + 6H2O → C6H12O6 + 6O2
- 3Stomata
- 4Oxygen
- 5Water and minerals
- 6Food (glucose)
- 73 × 6 = 18
- 8Xylem; it carries water and minerals up.
Nitrogen fixation and symbiotic nutrition
The soil around bean and groundnut plants is rich even after harvest, and farmers say these crops "feed" the soil. Lichens on old walls and tree trunks look like grey-green crusts, but they are two organisms living together.
Nitrogen fixation (नायट्रोजन स्थिरीकरण) is the conversion of gaseous nitrogen into forms plants can use. Symbiosis (सहजीवन) is two organisms living together for mutual help.
In the figure : In the figure of biological nitrogen fixation Rhizobium bacteria (B) live in the root nodules (A) of leguminous plants and convert nitrogen into nitrates.
Rule 1: Biological fixation — Plants cannot use gaseous nitrogen. Rhizobium in root nodules of leguminous plants and azotobacter in soil convert it to nitrates.
- Easy : Beans and groundnut have root nodules.
- Medium : Rhizobium lives in the nodules and makes nitrates.
- Exam-type : Azotobacter lives free in the soil and also fixes nitrogen.
In the figure : In the figure of atmospheric nitrogen fixation lightning forms nitric oxide, then nitrogen dioxide, which dissolves in rain as nitric acid and forms nitrates in the soil.
Rule 2: Atmospheric fixation — Lightning forms nitric oxide, then nitrogen dioxide, then nitric acid in rain, which forms salts in the soil.
- Easy : Lightning begins the process.
- Medium : Rain brings nitric acid to the soil.
- Exam-type : The order is: nitric oxide → nitrogen dioxide → nitric acid → salts (nitrates).
In the figure : In the figure of lichen the fungus (A) gives water, minerals and shelter (blue arrows C) to the alga (B), and the alga gives food (orange arrows D) to the fungus.
Rule 3: Symbiotic nutrition — Lichen = alga + fungus. The fungus gives water, minerals and shelter; the alga gives food by photosynthesis.
- Easy : Lichen is made of an alga and a fungus.
- Medium : The fungus gives water, minerals and shelter; the alga gives food.
- Exam-type : Both partners gain, so this is mutual help.
Fixation: Rhizobium and lightning. Lichen = alga + fungus (give and take).
Thinking plants take nitrogen gas directly from the air. They need nitrates.
Memory clue: Lichen: Alga = Food maker, Fungus = Flat (home) and water giver.
Spot the difference
| Process | Agent | Result |
|---|---|---|
| Biological fixation | Rhizobium, azotobacter | Nitrates in soil |
| Atmospheric fixation | Lightning and rain | Nitrates in soil |
| Lichen | Alga + fungus | Mutual benefit |
Practice questions
- 1What is nitrogen fixation?
- 2Which bacteria live in root nodules?
- 3Which plants have root nodules?
- 4How does lightning help nitrogen fixation?
- 5What is symbiosis?
- 6Which two organisms form a lichen?
- 7Who gives what in a lichen?
- 8A farmer grows groundnut after wheat and finds the soil richer. Explain with the reason.
Show answers (try them yourself first)
- 1Converting gaseous nitrogen into forms usable by plants.
- 2Rhizobium
- 3Leguminous plants like beans and groundnut.
- 4It forms nitric oxide, which finally gives nitric acid and nitrates.
- 5Two organisms living together for mutual help.
- 6An alga and a fungus.
- 7Fungus gives water, minerals and shelter; alga gives food.
- 8Rhizobium in groundnut root nodules fixes nitrogen into nitrates in the soil.
Heterotrophic plants and plant nutrients
Mushrooms pop up on a rotting log. A creeper winds around a tree and drinks from it. A pitcher plant waits with an open jar for insects. Plants that cannot make all their own food find other ways.
Heterotrophic plants (परपोषी वनस्पती) lack chlorophyll and get food from other sources. They may be parasitic, insectivorous or saprophytic.
In the figure : In the figure P is cuscuta, a completely parasitic plant. Q is a pitcher plant, an insectivorous plant. R shows mushrooms, saprophytes that digest dead remains.
Rule 1: Types of heterotrophic plants — Parasitic: cuscuta (completely), loranthus (partially). Insectivorous: Drosera, pitcher plant in nitrogen-poor soil. Saprophytic: fungi such as mushroom and yeast that feed on dead remains using enzymes.
- Easy : Cuscuta is completely parasitic.
- Medium : Loranthus is partially parasitic; it has green leaves but takes water from the host.
- Exam-type : Mushroom is a saprophyte: it digests dead remains with enzymes and absorbs the food.
In the figure : In the figure P is a healthy plant. Q: a lack of nitrogen gives stunted growth and yellow leaves. R: a lack of potassium gives a weak stem and wilting leaves.
Rule 2: Plant nutrient deficiency — Nitrogen: stunted growth, yellow leaves. Phosphorus: early leaf fall, slow root growth. Potassium: weak stem, wilting. Magnesium and iron: yellowing due to low chlorophyll.
- Easy : Yellow leaves and stunted growth: lack of nitrogen.
- Medium : Weak stem and wilting: lack of potassium.
- Exam-type : Slow root growth and early leaf fall: lack of phosphorus.
Heterotrophic plants have no chlorophyll: parasitic, insectivorous, saprophytic.
Thinking all insectivorous plants lack chlorophyll. Follow the lesson's grouping and remember insects supply nitrogen.
Memory clue: N – yellow and stunted; P – poor roots; K – weak stem.
Spot the difference
| Nutrient | Deficiency sign |
|---|---|
| Nitrogen | Stunted growth, yellow leaves |
| Phosphorus | Early leaf fall, slow root growth |
| Potassium | Weak stem, wilting |
Practice questions
- 1What are heterotrophic plants?
- 2Name a completely parasitic plant.
- 3Name a partially parasitic plant.
- 4Name two saprophytes.
- 5Why do insectivorous plants eat insects?
- 6A plant has yellow leaves and stunted growth. Which nutrient is lacking?
- 7A plant has a weak stem and wilting leaves. Which nutrient is lacking?
- 8Sunil says mushrooms make food by photosynthesis. Correct him.
Show answers (try them yourself first)
- 1Plants that lack chlorophyll and get food from other sources.
- 2Cuscuta
- 3Loranthus
- 4Mushroom and yeast.
- 5They grow in nitrogen-poor soil.
- 6Nitrogen
- 7Potassium
- 8Mushrooms have no chlorophyll; they digest dead remains with enzymes and absorb the food.
Nutrition in animals
When you eat a roti, many steps follow quietly: you chew, the roti breaks down, the body takes the useful part, and the rest leaves as waste. An amoeba does all this in a single cell.
Steps of nutrition in animals: ingestion → digestion → absorption → assimilation → egestion.
In the figure : In the figure the steps of nutrition in animals are ingestion, digestion, absorption, assimilation and egestion.
Rule 1: The five steps — Ingestion: taking food in. Digestion: breaking food down. Absorption: taking digested food into the blood. Assimilation: using it. Egestion: removing undigested waste.
- Easy : Chewing roti is ingestion.
- Medium : Breaking roti into simple sugars is digestion.
- Exam-type : Passing out undigested fibre is egestion.
Rule 2: Types of animal nutrition — Holozoic: herbivores, carnivores, omnivores, scavengers (vulture, crow) and decomposers. Saprozoic: absorbing liquid organic matter (housefly, ant, spider). Parasitic: ectoparasites (louse, tick, bed-bug) and endoparasites (tapeworm, roundworm).
- Easy : Vulture and crow: scavengers.
- Medium : Louse, tick and bed-bug live outside the body: ectoparasites.
- Exam-type : Tapeworm and roundworm live inside the body: endoparasites.
In the figure : In the figure of an amoeba all the steps happen inside one cell: the arms (A) surround the food, the food is digested in the food vacuole (B), and C is the nucleus.
Rule 3: Amoeba — In an amoeba all steps occur inside the single cell: arms surround the food, which is digested in the food vacuole.
- Easy : Amoeba: one cell does all five steps.
- Medium : Food vacuole is where digestion happens.
- Exam-type : An amoeba has no stomach, so the cell itself is its digestive system.
Order: ingestion → digestion → absorption → assimilation → egestion.
Mixing up egestion with excretion. Egestion removes undigested food; excretion removes waste made by the body.
Memory clue: I-D-A-A-E – Ingestion, Digestion, Absorption, Assimilation, Egestion.
Spot the difference
| Type | Feeding | Example |
|---|---|---|
| Holozoic | Takes in solid food | Cow, lion, vulture |
| Saprozoic | Absorbs liquid organic matter | Housefly, ant |
| Parasitic | Lives on or in a host | Louse (outside), tapeworm (inside) |
Practice questions
- 1Write the steps of nutrition in animals in order.
- 2What is ingestion?
- 3What is egestion?
- 4Name two scavengers.
- 5Name two ectoparasites.
- 6Name two endoparasites.
- 7Where does digestion happen in an amoeba?
- 8Housefly feeds on liquid organic matter. Which type of nutrition is this and why can an amoeba not be called the same?
Show answers (try them yourself first)
- 1Ingestion, digestion, absorption, assimilation, egestion.
- 2Taking food in.
- 3Removing undigested waste.
- 4Vulture and crow.
- 5Louse and tick (or bed-bug).
- 6Tapeworm and roundworm.
- 7In the food vacuole.
- 8Saprozoic; an amoeba engulfs food and digests it in a vacuole inside the cell (holozoic).
Quick revision
- Macro: carbohydrates, proteins, fats. Micro: minerals, vitamins.
- Xylem: water up. Phloem: food around.
- Lichen = algae + fungi.