CBSE Class 7 Science Nutrition in Plants Worksheets

Introduction

Plants and animals, for example, are all dependent on food. All living creatures require food to survive. We will deal with the nutritional needs of plants in this chapter. A nutrient is composed of carbohydrates, proteins, fats, vitamins, and minerals. Its major components are carbohydrates, protein, fat, vitamins, and minerals.

Mode of nutrition in plants

• Plants make their food by the use of different materials that are raw for example water, carbon dioxide and minerals.

• There are two modes of nutrition-

1. Autotrophic

2. Heterotrophic

1. Autotrophs or Autotrophic: - Plants that have chlorophyll trap the energy from the sun and prepare their own food. The nutrition that is there in the food which gets prepared by the other organisms is called autotrophic nutrition. An autotroph is a life form that has the capability of preparing its own food. Autotrophs are the form of plants that are green in color. Using a process called photosynthesis, they create their own food.

2. Heterotrophs or Heterophobic: - these kinds of substances are those that obtain their food from different organisms. As these kinds of organisms are dependent on other organisms for food, they are called consumers. Every animal and different non-green plants for example is fungi that come under the category in this form. Organisms that do follow the hetero module of nutrition are called heterotrophs.

• Those organisms that consume other organisms are heterotrophic organisms, also known as heterophobic organisms. 

The organisms listed above are known as consumers because they consume food from other organisms. Organisms that follow a heterotrophic mode of nutrition are heterotrophs. This classification includes animals and non-green plants like fungi.

• Photosynthesis

Chemical energy is produced by when light energy is converted by plants and other organisms via photosynthesis. Light energy is captured during photosynthesis, which is used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic molecules.

1. Green leaves of plants undergo photosynthesis.

2. Plant leaves are used to prepare a simple sugar called glucose which is extracted from the leaves of the plant.

3. Starches are made from the glucose in the plant leaves. Starches are stored in leaves.

4. Plants make carbohydrate energy from sunlight that causes them to be green.

Three Steps of Photosynthesis

There are three steps that are involved in photosynthesis. They are:

• A chlorophyll molecule that absorbs solar energy.

• Chemical energy is created by the conversion of light energy into chemical energy, and water is broken down into hydrogen and oxygen by light energy.

• Chemical energy is utilized to reduce carbon dioxide into carbohydrates such as glucose through the use of hydrogen.

The Significance  of Photosynthesis

• The parts of the plants that are green in color can also perform photosynthesis.

• Sugar, also known as glucose, is the simplest form of food produced by plants. By converting glucose into a complex carbohydrate called starch, plants produce complex carbohydrates.

• Simple carbohydrates are used for the synthesis of other components into the food like proteins and fats.

• Proteins can be categorized as nitrogenous compounds. Proteins are prepared by plants using soil nitrogen. 

• Water contains minerals that plants use to convert glucose (simple carbohydrates) into carbohydrates, proteins, and fats.

• Photosynthetic processes are important because they-

1. Sustain life on Earth and provide food for other organisms, including humans.

2. Humans, as well as other animals, need oxygen for breathing and respiration.

Heterotrophic Nutrition in Plants (Alternative forms of nutrition)

• The majority of plants produce their own food and contain chlorophyll as a pigment.

• They are known as heterotrophic plants because they lack chlorophyll and cannot create their own food.

• There are four types of heterotrophic nutrition.

1. A parasitic form of nutrition.

2. An insectivorous mode of nutrition.

3. Saprophyte mode of nutrition.

4. The symbiotic mode of nutrition.

Nutrient Replenishment in Soil

• The soil provides nutrients to plants as they synthesize food. This results in an overall reduction of nutrients in the soil.

• In soils, nutrients are replenished by adding manures and fertilizers.

• Fertilizers and manures do contain various plant nutrients and a decent amount of minerals like nitrogen, phosphorus and potassium.

• A Different method for the replenishment of soil is to grow leguminous crops (for example grams, peas, pulses etc.) within the soil.