NCERT Class 7 Science Chapter 1: Nutrition in Plants YouTube Lecture Handouts

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  • Nutrients – fats, vitamins, minerals, carbohydrates, proteins – required by our body

  • All living organisms require food

Mode of Nutrition

Nutrition is the mode of taking food by an organism

Image of Feeding Methods

Image of Feeding Methods

Image of Feeding Methods

Photosynthesis

  • Food making process in plants

  • Water & Minerals from soil

  • CO2 from air through small pores or stomata in leaves (surrounded by guard cells) – test potassium hydroxide absorbs carbon dioxide. (Starch test of leaf will show that leaf in air becomes blue black while that in flask with potassium hydroxide does not turn blue black)

Image of Photosynthesis

Image of Photosynthesis

Image of Photosynthesis

  • Transportation by vessels – xylem (water and minerals) and phloem (food)

  • Green pigment – chlorophyll

  • Photosynthesis – synthesis of food takes place in presence of sunlight (Sun is the ultimate source of energy for all living organisms)

  • If Sun absent – no photosynthesis – no food and no oxygen – life would be impossible

  • Desert plants – spine like leaves to reduce water loss by transpiration

  • The presence of starch in leaves indicates the occurrence of photosynthesis. Starch is also a carbohydrate.

  • Slimy, green patches in ponds or stagnant water bodies is algae which is makes its own food.

  • Carbohydrates are made of carbon, oxygen and hydrogen. These synthesize proteins (are nitrogenous substances) and fats.

  • Air has abundant nitrogen – fixation our in legumes in plants – converts gaseous nitrogen into usable form. With nitrogen they can now synthesize proteins and vitamins

Cell

  • Enclosed in cell membrane

  • Has cytoplasm

  • Centrally located – nucleus

Image of Cell

Image of Cell

Image of Cell

Heterotrophs

Parasitic Plants

  • Yellow wiry branched structure twining around the stem – called Cuscuta (Amarbel) – has no chlorophyll and depend on other trees – takes readymade food on the plant it is climbing (host). It deprives plant of its nutrient and hence is called as parasite.

  • All parasitic plants have modified roots (haustoria) which penetrate the host plants, connecting them to conductive system – either the xylem, the phloem, or both.

  • Example – Rafflesia, Dwarf Mistletoe, Australian Christmas Tree

Image of cuscuta

Image of Cuscuta

Image of cuscuta

Insectivores Plants

  • Pitcher plant – Lid that closes & insect killed by juice that is secreted in pitcher and nutrients are absorbed

  • These plants are usually associated with rain-washed, nutrient-poor soils, or wet and acidic areas that are ill-drained – so have to hunt for food

  • Others – Utricularia, Drosera, Aldrovanda

Image of Nepenthaceae - pitcher plant

Image of Nepenthaceae - Pitcher Plant

Image of Nepenthaceae - pitcher plant

Saprophytes

  • Mushrooms – fluffy umbrella like patches on moist soil or rotting wood

  • Take nutrient from dead and decaying matter like fungi

  • Examples: Rhizopus (bread mould), mucor (pin mould), Yeast, and Agaricus (mushroom)

Image of mushroom

Image of Mushroom

Image of mushroom

  • Seen in hot and humid climate

  • Fungal spores are present in atmosphere, when they land on wet and warm things they germinate

Symbiosis

Table of Symbiosis
Table of Symbiosis

Mutualism

+

+

Commensalism

+

0

Parasitism

+

-

Neutralism

0

0

Amensalism

-

0

Competition

-

-

Organisms live together and mutually benefit one another

Fungi live inside the roots of plants. The plants provide nutrients to the fungus and, in return, the fungus provides water and certain nutrients.

Lichens (Algae and fungi): fungus provides shelter, water and minerals to the alga while alga prepares and provides food to the fungus.

Image of Symbiotic Relationships

Image of Symbiotic Relationships

Image of Symbiotic Relationships

Image of relation like symbiosis commensalism

Image of Relation like Symbiosis Commensalism

Image of relation like symbiosis commensalism

Replenish Nutrients in Soil

Spread of Manures or Fertilizers

Image of Manure and Fertilizer
Image of Manure and Fertilizer

Manure

Fertilizer

Manure is a natural material, obtained by decaying plant and animal waste - enhance its fertility.

Fertilizer is a human-made or natural substance - added to the soil to improve its fertility and increase productivity.

It provides humus to the soil.

It does not provide humus to the soil.

Comparatively less rich & slowly absorbed by soil

Rich in plant nutrients & is quickly absorbed by plants

It is economical

It is costly

  • Contain nutrients like N, P and K- timely addition for healthy growth of plants

  • Bacterium called Rhizobium can take atmospheric nitrogen and convert it into a usable form.

  • Symbiotic Relation: Rhizobium cannot make its own food. So it often lives in the roots of gram, peas, moong, beans and other legumes and provides them with nitrogen. In return, the plants provide food and shelter to the bacteria

Image of rhizobium in root nodules

Image of Rhizobium in Root Nodules

Image of rhizobium in root nodules

Rhizobium in root nodules