Notes: Plants | EVS & Pedagogy Paper 1 for CTET & TET Exams - CTET & State TET PDF Download

Plants are living things that grow in the ground. They need sunlight, water, air, and soil to grow. Plants have different parts like roots, stems, leaves, flowers, and fruits. Roots help plants stay in the soil and absorb water and nutrients. Leaves make food for the plant through a process called photosynthesis. Flowers can turn into fruits, which contain seeds to grow new plants. Plants are important because they give us oxygen to breathe and food to eat. 

• Plant is very broad and it includes single celled algae to flower and fruit bearing trees.
• Plants may be terrestrial or aquatic, plants which are present on the land surface is called terrestrial plant.
• Plant which floats, submerged or remain suspended in water is called aquatic plants.

Different Parts of Plants

The entire structure of a plant is divided into different parts, each performing distinct functions. The different parts of plants are as follows:

I. Root System

The root system helps in the absorption of water and nutrients from the soil, which are essential for the growth of the plant.

• Radicle: The first root that emerges from a plant is called the radicle.
• Root Hairs: Tiny hair-like structures on the roots that increase the surface area for absorption.

The root system consists of roots, root hairs, and all their parts.

There are two main types of root systems:

1. Tap Root System

• Characteristics: A large, central, and dominant root from which other roots sprout laterally.
• Development: Tap roots develop from the radicle of a seed, forming the primary root. This primary root branches into secondary roots and further into tertiary rootlets.

Modification of Tap Roots for Storage of Carbohydrates

• Conical Root: Examples include carrot.
• Fusiform Root: Examples include radish.
• Napiform Root: Examples include turnip.

Tap roots are also important adaptations for searching for water, as seen in plants like mesquite and poison ivy.

2. Fibrous Root System 

• Characteristics: Thin, moderately branching roots growing from the stem.
• Examples: Coconut, grass, and onion.

Functions of the Plant Root

• Anchorage and Support: The plant root system anchors the plant body to the soil and provides physical support. In general, however, taproot systems provide more effective anchorage such that they are more resistant to toppling during storms.
• Absorption and Conduction: The plant root system absorbs water, oxygen, and nutrients from the soil in mineral solution, mainly through the root hairs. They are capable of absorbing inorganic nutrients in solution. Plants with a fibrous root system are more efficient in absorption from shallow sources.
• Storage: Some roots store food as carbohydrates, examples include potato, sweet potato, carrot, turnip, etc.
• Vegetative Reproduction: Roots also help in vegetative reproduction, examples include jasmine and grass.
• Prevention of Soil Erosion: The plant root system keeps soil integrated and prevents soil erosion during heavy rain.

Modification of Root

1. Prop Roots:

• These roots grow vertically downwards from aerial branches to provide additional support.
• They are commonly seen in banyan trees.

2. Stilt Roots:

• Aerial adventitious roots that grow obliquely downwards from the basal nodes of the main stem and enter the soil.
• Examples include maize and sugarcane.

3. Pneumatophores:

• These are geotropically negative (growing away from gravity) respiratory roots.
• Pneumatophores are primarily found in mangrove plants or plants that grow in swampy areas, such as Rhizophora and Avicennia.

II. Shoot System

The shoot system is the part of the plant that is above the ground. It includes the stem, leaves, flowers, fruits, and seeds. The main functions of the shoot system are to support the plant, conduct water and nutrients, and produce food through photosynthesis. 

The stem is the part of the plant that supports the leaves, flowers, and fruits. It also conducts water and nutrients between the roots and the rest of the plant. The leaves are the main site of photosynthesis, where the plant makes food from sunlight, carbon dioxide, and water. The flowers are the reproductive organs of the plant, where pollination and fertilization occur. The fruits protect the seeds and help in their dispersal. The seeds contain the embryo of the new plant and are responsible for the next generation.

1. Stem

The stem is the part of the plant that grows upward from the ground and supports the branches, leaves, flowers, and fruits. It develops from the plumule of the germinating seed. The main functions of the stem include:

• Support: The stem provides support to the plant, helping it to stand upright and grow tall.
• Transportation: The stem transports water, minerals, and photosynthates (products of photosynthesis) between the roots and the other parts of the plant.
• Storage: Some stems, like those of sugarcane, store food.
• Vegetative propagation: Certain stems can produce new plants without seeds, such as in sugarcane.
• Protection: The stem can protect the plant from pests and diseases.

Types of Stems

There are two main types of stems: erect stems and weak stems.

A) Erect Stem

• An erect stem grows straight up without any support. It is strong and can support the weight of leaves, flowers, and fruits.
• Examples of plants with erect stems include bamboo and the banyan tree.

B) Weak Stem

A weak stem is unable to grow upright on its own. It either trails on the ground or climbs with the help of supports. Weak stems are further classified into:

(i) Climbers

• These stems climb with the help of tendrils, hooks, spines, prickles, or roots.
• Examples include pea, passion flower, and vine.

(ii) Twiner

• A twiner is a weak stem that grows by coiling around a support.
• An example is Ipomoea palmata.

(iii) Trailer

• Trailer plants have weak, long, and slender stems that trail along the ground.
• They do not climb and do not root from the nodes.
• Examples include portulaca and evolvulus.

(iv) Creeper

• Creeper plants have stems that creep on the ground.
• They may be runners, stolons, offsets, or suckers.
• An example is grasses.

Functions of the Stem

The stem plays a crucial role in the growth and development of the plant by performing the following functions:

• Support: The stem supports the leaves, flowers, and fruits, connecting them to the roots. In trees and shrubs, the main stem or trunk provides a strong, upright structure from which branches are attached, raising the leaves to expose them more fully to sunlight.
• Transportation: The stem conducts water, nutrients, and the products of photosynthesis between the roots and leaves. It accommodates the transport system necessary for the vertical and lateral movement of water and sap within the plant.
• Storage: The stem can store water, as in cacti, and the products of photosynthesis, such as starch, as seen in the trunks of sago palm(Metroxylon sagu) and sweet palm(Arenga pinnata).
• Photosynthesis: Young green stems can perform a minor role in photosynthesis, but in some species, like cacti, the stem is the chief photosynthesizing organ.
• Asexual Reproduction: In many plant species, the stem serves as a means of asexual reproduction.
• Food Transfer: The stem translocates organic food from the leaves to the rest of the plant.

2. Bud

A bud is an undeveloped shoot that typically occurs in the axil of a leaf or at the tip of a stem. The stem of a bud is very short, and its leaves are tightly packed, overlapping each other. The inner leaves are crinkled and folded to fit into the small space, while the outermost leaves, known as bud scales, are often thicker and tougher. These scales protect the delicate inner leaves from drying out, damage by birds, insects, or fungi, and to some extent, from temperature extremes. At the end of the bud's short stem, there is either a flower or a growing point where rapid cell division will occur later when the next bud is forming.

Types of Bud

There are three main types of buds:

A) Terminal Bud

• A terminal bud is located at the tip of a stem. It is responsible for the upward growth of the plant.

B) Axillary Bud

• An axillary bud is found in the axil of a leaf where the leaf joins the stem. Axillary buds can develop into branches or flowers.

C) Adventitious Bud

• An adventitious bud occurs in unusual locations, such as on the trunk or roots of a plant. Some adventitious buds may be former axillary buds that are now hidden under the bark, while others are completely new formations.
• Cablage is a specific type of bud.
• Cloves are aromatic flower buds used as a spice.

3. Leaf

Different plants have specific types of leaves. Leaves are the main sites of photosynthesis. They take up carbon dioxide (CO2) from the atmosphere, water and other nutrients from the soil, and energy from sunlight. The color of leaves is green due to the presence of the pigment chlorophyll. When the amount of chlorophyll in leaves decreases, the color of the leaves can change, often turning yellow. 

Functions of Leaves

Some important functions of leaves include:

• Manufacture of Food: The primary function of green leaves is to manufacture food through a process called photosynthesis. This process occurs in the presence of sunlight and the green pigment chlorophyll. Leaves use water and carbon dioxide to prepare food materials. Since plants make their own food using light, they are called autotrophs.
• Respiration and Photosynthesis: Leaves have numerous tiny openings called stomata, which allow for the exchange of gases between the atmosphere and the plant. Both respiration and photosynthesis take place through these openings.
• Evaporation of Water: Water absorbed by the root hairs of the plant is evaporated from the leaf surface during the daytime. This process, known as transpiration, usually occurs through the stomatal openings. Transpiration helps the plant absorb water and minerals from the soil and conduct them to the top of the plant.
• Storage of Food: Fleshy leaves of plants like Indian aloe and portulaca, as well as the fleshy scale leaves of onion, store food materials and water for future use. Fleshy and succulent leaves of xerophytic plants in desert areas store large quantities of water, mucilage, and food materials.
• Vegetative Propagation: Leaves of plants like Bryophyllum, Begonia, and Kalanchoe can produce buds that give rise to new plants through vegetative propagation. When the leaf lamina touches the ground, the leaf margin produces roots and forms a bud that grows into a new plant.

4. Flower

A flower is the reproductive unit in angiosperms. A typical flower has four different whorls arranged on the swollen end of the stalk or pedicel called the thalamus or receptacle. These four whorls are the calyx, corolla, androecium, and gynoecium. Flower

Parts of a Flower

• Calyx: The calyx is the outermost whorl of the flower, and each part of the calyx is called a sepal. Sepals are green, leaf-like structures that protect the flower in its bud stage.
• Corolla: The corolla is composed of petals, which are often brightly colored to attract insects such as butterflies and honeybees for pollination.
• Androecium: The androecium is composed of stamens. Each stamen consists of a stalk or filament and an anther. Meiosis occurs in the anther, producing pollen grains.
• Gynoecium: The gynoecium is the female reproductive part of the flower, made up of one or more carpels. A carpel consists of three parts: the stigma, style, and ovary. The ovary is the enlarged basal part of the carpel, on which an elongated tube called the style lies. The style connects the ovary to the stigma, which is usually at the tip of the style and serves as the site for pollen grain reception.

5. Fruit

A fruit is a mature or ripened ovary developed after fertilization. It is a seed-bearing structure in flowering plants. Fruits protect the enclosed seeds and aid in their dispersal. For example, apples and figs are not true fruits because the edible part is the thalamus, not the ovary.

III. Different Types of Plants

Plants can be classified based on various criteria, such as physical characteristics, life span, and the regions where they are found. Below are the classifications of plants based on these criteria:

On the Basis of Physical Structure

• Herbs: Delicate, seed-bearing plants with non-woody stems that cannot stand erect. Herbs are commonly used for flavoring food, as medicines, and in perfumes. Examples include brinjal, coriander, tomato, and tulsi.

• Shrubs: Small to medium-sized woody plants with multiple main stems arising at or near the ground. Examples include rose, bougainvillea, and cotton.
• Trees: Strong, woody plants with a single trunk that supports branches. Trees can be very tall or of medium height. Examples include mango trees and banyan trees.
• Climbers: Plants with weak stems that require support to grow. Examples include money plant, grapevine, and pea.
• Creepers: Plants with weak stems that spread along the ground. Examples include watermelon, pumpkin, and bottle gourd.

On the Basis of Life Span

• Annual Plants: Plants that complete their entire life cycle within a year, from seed germination to seed production. Examples include wheat, maize, and sunflower.
• Biennial Plants: Plants that take two years to complete their life cycle. In the first year, they grow roots, stems, and leaves, and in the second year, they bear flowers. Examples include carrot and radish.
• Perennial Plants: Plants that live for many growing seasons. Their roots develop over a large area. Perennial flowering plants grow and bloom in spring and summer, shedding their leaves in autumn and winter. Examples include mango and apple trees.

On the Basis of Region

• Hydrophytes: Plants that grow in or on water. They have adaptations such as thin cuticles, large flat leaves, air sacs for flotation, reduced roots, and waxy coatings on leaves. Examples include lotus, hydrilla, and water lily.
• Xerophytes: Plants that grow in areas with limited water supply, such as deserts. They typically have deep roots, pointed, waxy, and small leaves, thick cuticles, and fewer stomata for increased water storage.
• Mesophytes: Plants that grow in environments that are neither very dry nor very wet. Examples include mango and neem trees. These plants may not survive floods because their roots cannot respire properly.
• Halophytes: Plants that grow in water with high salinity, such as in saline semi-deserts, mangrove swamps, marshes, and seashores. These plants often have roots that grow above the surface of the land. An example of a halophyte is rhizophora.

Significance and Importance of Plants

Earth is often referred to as a green planet because of the abundance of plants. In fact, plants are considered to be among the first living organisms to appear on our planet. They play a crucial role in various aspects of our environment and well-being. Here are some of the key benefits and roles of plants:

1. Gaseous Balance and Photosynthesis

• Photosynthesis: Plants help maintain the balance of gases in the air through the process of photosynthesis. They absorb carbon dioxide (CO2) emitted by animals and release oxygen, which is essential for the survival of most living organisms.

2. Environmental Regulation

• Plants contribute to regulating temperature, preventing soil erosion, maintaining ecological balance, supporting rainfall, and preserving soil fertility through various mineral and water cycles.

3. Habitat for Wildlife

• Plants provide shelter and habitat for various animals, including birds, monkeys, squirrels, and many other species. This biodiversity is essential for a healthy ecosystem.

4. Autotrophic Nature

• Plants are called autotrophs because they produce their own food using sunlight, chlorophyll, carbon dioxide, and water. They provide a wide range of food sources for humans and animals, including carbohydrates, fats, proteins, vitamins, and minerals.

5. Oil Production

• Plants are a source of various edible oils, such as mustard oil, groundnut oil, coconut oil, and sunflower oil. These oils are primarily obtained by crushing seeds, although some oils of commercial importance are extracted from leaves and fruits.

6. Medicinal Value

• Many plants have significant medicinal value. For example, plants like Tulsi, neem, garlic, aloe vera, cinchona, and poppy are known for their health benefits and are used in traditional medicine.

7. Edible Flowers

• Some flowers are consumed as food in different regions of India. For instance, kachnar in Uttar Pradesh, banana flower in Kerala, and sahjan flower in Maharashtra are examples of edible flowers.

8. Wood and Fiber Production

• Wood: Plants like teak, sal, and sesam provide wood for various uses. Plants like bamboo are used for making paper, while plants like babul, acacia, and kikar produce gum. Plants like cotton and jute provide fiber for making cloth, bags, and ropes.

9. Beverages and Spices

• Plants are the source of various beverages and spices, including tea, coffee, and alcoholic drinks. They also provide a wide range of spices, perfumes, dyes, and natural colors.

10. Nutrient Sources

• Cereals: Rice, wheat, millet, maize, barley, and oats are important cereal crops.
• Pulses: Various types of grams, such as arhar, moong, and horsegram, are important sources of protein.
• Roots: Vegetables like radish, turnip, carrot, and beetroot are consumed for their nutritional value.
• Stems: Plants likeginger, garlic, potato, andonionare important sources of food.
• Leaves: Vegetables like cabbage and spinach are consumed for their nutritional benefits.
• Nuts: Nuts like almonds, walnut, cashew nut, and peanut are important sources of healthy fats and proteins.

In summary, plants are not only essential for maintaining ecological balance and providing food but also contribute significantly to our economy and health through various products and services. Their role in sustaining life on Earth cannot be overstated.

Special Plants and Their Features

Plants have unique adaptations that help them survive in different environments. Here are some special plants and their distinctive features:

1. Desert Oak

• The Desert Oak is a medium-sized, slow-growing tree found in the dry desert regions of Northern Territory, South Australia, and Western Australia.
• Adaptation: It has deep roots that extend three times the length of the tree to search for underground water. Instead of traditional leaves, it has long, segmented branchlets. Indigenous Australians have used this tree as a source of water.

2. Nepenthes (Pitcher Plant)

• The Nepenthes, or Pitcher Plant, is a carnivorous and insectivorous plant that traps insects, frogs, and even small mammals in its pitfall trap.
• Adaptation: It has a modified leaf that forms a cavity over its pitfall trap. To attract insects, it emits a pleasant smell. Although it can perform photosynthesis due to the presence of chlorophyll, it supplements its nitrogen intake by digesting insects. Other examples of insectivorous plants include the Viral Fly Trap and Sundew Plant (Drosera).

3. Khejri Tree (Prosopis Cineraria)

• The Khejri Tree, also known as the Prosopis Cineraria, is the state tree of Rajasthan. Environmentalists have raised concerns about its declining population.
• Significance: It covers about two-thirds of the total geographical area of Rajasthan and supports the rural economy. Its fruits are a rich source of protein, and its bark is used for medicinal purposes. The wood of the Khejri Tree is resistant to insect damage.

4. Banana

• Contrary to popular belief, the banana stem is not a true stem but a flower stalk of the banana plant.
• Classification: Banana is classified as a herb. Both the flower and fruit of the banana plant are edible.

5. Croton

• Croton is used as an indicator plant for water deficiency.
• Method: When croton leaves begin to wilt, it signals the need for water in nearby crops.

6. Banyan Tree

• Life Cycle: The banyan tree begins its life as an epiphyte, growing on another plant.
• Support: As it matures, old banyan trees develop aerial prop roots that act as pillars, providing support to the tree.

7. Introduction of Plants to India

• Some plants have their origins in South America and were introduced to India, including tomato, potato, and green chili.
• Plants like cabbage, orange, and pea were brought from Europe, while bhindi(okra), coffee, and bean were introduced from Africa.

These examples highlight the incredible diversity of plants and their unique adaptations to survive and thrive in various environments.

Nutrient in Plants

Plants can be classified into two groups based on their nutrient habits: autotrophs and heterotrophs.

1. Autotrophs

• Autotrophs are plants that can produce their own food using light, water, and carbon dioxide (CO2). Because they produce their own food, they are sometimes called producers.
• Examples of autotrophic plants include green plants that photosynthesize and some types of algae.

2. Heterotrophs

Heterotrophs are plants that cannot prepare their own food and are dependent on other plants and animals for their nutrition. They can be further divided into the following types:

(i) Parasites

• Parasitic plants cannot synthesize their own food because they lack chlorophyll. They have specialized structures called sucking roots that allow them to take prepared food from their host plants.
• Examples of parasitic plants include cuscuta(dodder) and broomrape.

(ii) Saprophytes

• Saprophytic plants grow on decaying organic matter, such as dead plants or animals, and absorb organic food material from this matter.
• Examples of saprophytic plants include mushrooms, monotropa(a type of Indian pipe plant), bacteria, and fungi.

(iii) Symbionts

• Symbiotic plants are two organisms that live in close physical association and benefit each other. For example, lichens are a symbiotic association between a fungus and an alga or cyanobacterium.
• Mycorrhizae is another example where a fungus forms a symbiotic relationship with the roots of a plant, aiding in nutrient absorption.

(iv) Insectivorous Plants

• Insectivorous plants grow in swampy soil that is deficient in nitrogen. To obtain nitrogen, they eat small insects.
• These plants can also perform photosynthesis. Examples of insectivorous plants include Pitcher Plants (Nepenthes), Sundew (Drosera), and Venus Fly Trap.

Food Chain

A food chain illustrates the feeding relationships among different organisms within a specific environment or habitat. At the base of any food chain are plants, which produce their own food through the process of photosynthesis. 

Producers and Consumers

• Producers: Plants are known as producers because they create their own food using sunlight, water, and carbon dioxide.
• Herbivores (Primary Consumers): These are animals that eat plants. They are the first level of consumers in the food chain.
• Carnivores (Secondary Consumers): These animals eat herbivores. They are the second level of consumers.
• Tertiary and Quaternary Consumers: These are animals that eat other carnivores or herbivores, and they occupy higher levels in the food chain.

Role of Decomposers

Decomposers, although not depicted in the food chain, play a crucial role by breaking down dead organic matter and converting it into inorganic matter. This process is essential for recycling nutrients back into the ecosystem.

Importance of Plants in Child Development

Understanding Human Survival

By learning about the various roles that plants play in the life of humans and animals, such as providing oxygen and food, children can grasp the fundamental importance of plants for human survival.

Sensitivity Towards Nature

Studying the role of plants in nature helps children become more sensitive and aware of the environment, fostering a sense of responsibility towards nature.

Curiostity and Interest in Plants

Observing the growth and development of plants can spark curiosity in children, motivating them to learn more about plants and their life processes.