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Plants exist everywhere around us. Their existence is vital to our survival. A wide variety of plants can be found in the world. Some of them are small, while the others are huge. They are the only living species that produce their own food by the process called photosynthesis while other species directly or indirectly depend on plants for food and survival.
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Key Takeaways: Soil, Photosynthesis, Roots, Stem, Leaves, Flowers, Fruits, Stomata, Seeds, Germination.
Explanation of Plants
Plants are living species that belong to the kingdom of Plantae and grow in soil while remaining fixed to a particular location with the help of its roots. They have a multicellular, photosynthetic and eukaryotic (their cells have a nucleus and other organelles) existence. Plants can be of different shapes, sizes, structures and colours.
Parts of a Plant
The plant is broadly divided into two parts:
- The Root System
- The Shoot System
Parts of a Plant
Root System
It is the part of the plant that goes under the soil i.e., the underground part. It mainly consists of the roots that grow below the soil.
Types of Roots
Roots are classified into two types. They are:
- Taproots: It has a main root that originated from the base of the stem and multiple other smaller roots that are attached to the main root.
- Fibrous Roots: In this type, all roots are similar and attached to the base of the stem. They do not have a main root.
Types of Roots
Functions of the Root
- To provide support to the plant
- To provide the plant with water and other necessary nutrients from the soil
- Store food for the plant
- Help in conduction of water and nutrients from soil to the main stem/bark
- Promote vegetative reproduction
Shoot System
It is the aerial part of the plant that exists above the soil. It grows against gravity. It includes the stem, leaves, flowers, fruits and buds.
Shoot System
Stem:
It is a long, supportive, central axis of the plant that grows vertically upwards from the ground. It stands perpendicular to the ground on its own.
The primary functions of the stems are:
- To provide support and elevation to leaves, fruits and other parts of the plant
- To transport water and nutrients from the roots to other areas
- To facilitate various biochemical processes
- To provide a strong foundation and structure to the plant
- To provide a place for the prepared food to be processed in the starch form
Leaves:
It is one of the most important parts which is also called the food factory or kitchen of the plant. They are flat, mostly green organs that are responsible for photosynthesis. It has tiny pores over it called the “stomata”.
The main functions of the leaves are:
- To facilitate photosynthesis, the process through which the plant produces food and energy
- To enable the plant to breathe via stomata
- To facilitate removal of excess water through transpiration
Flowers:
These are the colourful parts of the plant. They are responsible for reproduction as they have reproductive organs in them. They also facilitate pollination and formation of fruits.
Also Read: Sexual Reproduction
Fruits:
This part of the plant carries the seed. They are developed from the ovaries that are present in the flowers. They help in the seed formation and removal of matured seeds. They can also be consumed by humans.
Classification of Plants:
Plants can be classified on the basis of the following criteria:
Based on Reproduction:
- Flowering Plants: They have flowers in them. Seeds in such plants are inside the fruit.
Example: Banana, Mango, Apple, etc.
- Non-Flowering Plants: They do not have flowers and have naked seeds.
Example: Cypress, pine, etc.
Based on Life Cycle:
- Annuals: They finish their entire life cycle in a single season.
Example: Rice, Peas, Wheat, etc.
- Biennials: They finish their life cycle in two years.
Example: Carrot, Onions, Beetroot, etc.
- Perennials: They live a long life and finish their life cycle in more than two years.
Example: Lavender, Rose, Lilies, etc.
Also Read: Difference between photosynthesis and respiration
Based on their Growth Habitats:
- Herbs: These plants are very short.
Example: Grass, Mint, etc.
- Shrubs: They are medium sized plants.
Example: Lemon, Rose, etc.
- Trees: These are tall and huge. A normal sized tree can produce about 1,70,100 pencils.
Example: Mango, Banyan, etc.
- Climbers: These are delicate and require support.
Example: Money plants, pea plants, etc.
- Creepers: They have weak stems and hence stay on the ground.
Example: Watermelon, Pumpkin, etc.
Also Read: Plant and Tree
Life Cycle of a Plant
Seed
(Seed gets planted into the soil)
↓
Germination
(Sprout comes out from seed)
↓
Roots and Stem
(Roots and stem start developing)
↓
Seedling
(Plants bears leaves and root elongates)
↓
Pollination
(Fully grown plant that produces flowers and begins reproduction process)
Also Read:
Things to Remember:
- Seeds require proper conditions of water, air, sunlight to grow into a fully grown plant.
- There can be no survival of most species including humans without plants because it is the only source of oxygen and food.
- There are about 3,20,000 species of plants in this world.
- Plants possess a waxy layer called cuticle that prevents excess transpiration and drying out.
Sample Questions
Ques 1. Why are the leaves of most plants green? [2 marks]
Ans. There exists a chemical known as the chlorophyll in the leaves due to which their colour turns green. This chemical facilitates the biochemical process called photosynthesis and helps the plant to grow using the air, water and light provided by the sun. It produces energy by absorbing light. This chemical gives green colour because it absorbs all portions of the electromagnetic spectrum and emits the green portion.
Ques 2. What are the main requirements of a plant? [5 marks]
Ans. The primary requirements of a plant include sunlight, air, water, nutrition and optimal temperature.
- Sunlight helps the plant to prepare its own food.
- Carbon dioxide (necessary for photosynthesis) comes from air.
- Water helps the plant to stay hydrated and also assists food preparation.
- Nutrients are also required for proper growth and immunity of the plant. It also helps them in reproduction.
- Many chemical reactions take place only at certain ranges of temperature. Hence, temperature becomes a key factor for proper development.
Ques 3. How does a seed grow into a new plant? [2 marks]
Ans. All seeds contain an embryo inside them which is protected by a seed coat. Once the seed is put inside soil and provided with the right amounts of water, nutrients, moisture and temperature, it breaks open through the seed coat and a small root comes out. Later, the shoot also emerges from the seed. It continues growing and develops leaves and smaller roots and fixes itself into the soil. Proper care should be taken during germination lest the seed turn dormant.
Ques 4. State some uses of the plant. [4 marks]
Ans. Plants are the source of almost every requirement of humans. Some of the important uses are:
- It provides food to us.
- It provides oxygen and also makes the air purer to breathe.
- It provides wood to make furniture.
- Cotton is obtained from plants which is used in clothes, bed-sheets, etc.
- Fibre from plants is used to make jute bags, ropes, etc.
- Medicinal plants like basil, neem, etc. help treat injuries and diseases naturally.
- Plants with strong aroma are used to make perfumes and other scents.
- Paper and rubber are also made from plants.
Ques 5. What are herbs? [3 marks]
Ans. Herbs are a type of plant that are small in size and have a very soft stem. Their maximum height can be about 1.5 metres. Since the stems are fragile, it is generally not woody and can be bent easily. This type of plant may or may not have branches. Most herbs also possess savoury or aromatic characteristics which is why they are used for culinary and medicinal purposes.
Some examples of herbs are: tomato, mint, basil, etc.
Ques 6. What is transpiration? [2 marks]
Ans. Transpiration is the process through which the plants release excess water through stomata. This occurs when the leaves absorb an extra amount of water from the soil. This water exits the plants from the underside of the surface of the leaf in the form of water vapours. Transpiration is also known as evaporation of water from leaves of the plant. It helps to keep the plant cool during summers and also keeps its environment humid.
Ques 7. Can roots be consumed by humans? [3 marks]
Ans. Roots are an edible part and can be very healthy and delicious. It contains high amounts of nutrients, especially starch. Although, proper care has to be taken to remove any and all soil from the roots and to properly clean it before consuming. Identified roots of only non-contaminated soil should be eaten. Cooking before consuming roots is advised as it removes any extra harmful elements.
Some examples of edible roots are: carrots, onions, potatoes, etc.
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