Nutrition in Plants
Overview
Plants make their own food — this is called photosynthesis. But not all plants do this — some are parasitic on others, and some even eat insects! In this chapter, we will learn different ways in which plants obtain their nutrition.
Typed Notes
Photosynthesis — the plant's kitchen
The leaf is the plant's kitchen. The recipe: chlorophyll (the green pigment — absorbs sunlight) + water (absorbed by roots, travels up the stem) + carbon dioxide (from the air — enters through stomata). In the presence of sunlight, all these combine to produce glucose (food) and release oxygen. This is why: (1) plants grow towards light; (2) the leaf is green — it is rich in chlorophyll; (3) cutting down forests = cutting down oxygen. The energy produced through photosynthesis is the foundation of the entire food chain.
Stomata, minerals, and the pathway of water
The surface of leaves has very tiny pores called stomata — CO2 enters through them, and oxygen and water vapour exit through them. Water travels from the roots, up the stem, and reaches the leaves; the leaves prepare food and send it to all parts of the plant. Some plants (like cactus) have fewer leaves — to conserve water. Leaves keep making food throughout the year — which is why plants always need sunlight and water.
Parasites, saprotrophs, and insectivores
Not all plants make their own food: (1) Parasitic — Cuscuta (dodder): it twines around a host plant and steals its food by penetrating the host's tissues — it has no chlorophyll at all. (2) Saprotrophs — organisms that grow on decaying matter: mushroom, and the mould that grows on bread — they absorb nutrients from decaying material. (3) Insectivorous — pitcher plant: its leaves are shaped like a pitcher, with sweet liquid inside — an insect lands on it — the opening closes — the insect gets digested — the plant absorbs nitrogen (because its soil lacks nitrogen).
Symbiosis — nitrogen through friendship
Symbiosis = a relationship between two organisms in which both benefit. (1) Lichen = partnership of algae + fungi: algae makes food (through photosynthesis), fungi provides water and shelter — together they can survive in harsh places like deserts and mountains. (2) Rhizobium bacteria — forms nodules on the roots of leguminous crops (pulses — chickpea, moong, lentil) and fixes nitrogen from the air — the plant gets fertiliser, the bacteria gets a home and food. This is why farmers rotate crops — pulses followed by wheat — so that nitrogen is restored in the soil.
Key Concepts
Revision ke liye ek nazar — exam se pehle yahi padhna hai.
- 01Photosynthesis: the leaf (chlorophyll) uses sunlight + water + CO2 to make glucose and releases oxygen. Stomata — tiny pores on leaves, act as the doorway for CO2.
- 02Plants make their own food — so they are called producers; other living beings depend on them — they are called consumers.
- 03Parasitic plant: lives on another plant — Cuscuta (dodder) — takes food from the host; has no chlorophyll.
- 04Insectivorous plant: eats insects — pitcher plant — because the soil it grows in lacks nitrogen.
- 05Saprotrophs: grow on decaying matter — mushroom, bread mould. Symbiosis: a mutually beneficial relationship between two organisms — lichen (algae + fungi); Rhizobium bacteria on the roots of legumes — fixes nitrogen.
Questions & Solutions
Pehle khud try karo — phir solution kholo. Yahi tariqa topper banata hai.
Write the equation of photosynthesis in words — what is needed and what is produced?
How does Cuscuta (dodder) obtain its food?
Why does the pitcher plant eat insects even though it is a plant?
What organisms live together in lichen and what is the benefit?
Why does a farmer sow wheat after a pulse crop?
What are stomata and what is their function?
Photosynthesis: chlorophyll + sunlight + water + CO2 → glucose + oxygen (through stomata). Parasitic plants (Cuscuta) steal food, saprotrophs (mushroom) grow on decaying matter, and insectivorous plants (pitcher plant) obtain nitrogen from insects. Symbiosis: lichen, Rhizobium on legume roots — both organisms benefit.
Chapter-end quiz
4 MCQsOption tap karo — turant pata chalega sahi ya galat, explanation ke saath.
Q1.What does a plant release during photosynthesis?
Q2.What type of plant is Cuscuta (dodder)?
Q3.Why does the pitcher plant eat insects?
Q4.What is the partnership of algae and fungi in lichen called?
Mark karo — dashboard par progress dikhega.