Grade 7 Chapter 1: The Living World: Adaptations and Classification

Introduction

The living world is incredibly diverse, with organisms found in nearly every environment on Earth. From the highest mountains to the deepest oceans, life has adapted to survive and thrive. This chapter explores how living organisms develop special features or behaviors to live successfully in their surroundings, a process called adaptation. We will also learn how scientists group these organisms based on their similarities and differences, which is known as classification.

Adaptations in Plants

Adaptations in Aquatic Plants

Aquatic plants show various adaptations to live in water. Some are entirely submerged, some are partially submerged, and some float on the surface.

• Submerged Plants: Have narrow, thin leaves to reduce resistance to water currents. Their stems and leaves are flexible.
• Floating Plants: Have leaves with waxy coatings to repel water and prevent rotting. Their stems are often hollow and flexible to help them float. Examples include water lily and lotus.
• Roots: Roots of aquatic plants are often reduced in size and function primarily to anchor the plant, not to absorb water and nutrients, as they are directly available from the surrounding water.

Adaptations in Desert Plants

Desert plants, like cacti, are adapted to conserve water in arid conditions.

• Leaves: Many desert plants have very few leaves, or their leaves are modified into thorns or spines to reduce water loss through transpiration.
• Stems: Stems are often thick and fleshy, storing water and performing photosynthesis in the absence of leaves.
• Roots: Roots penetrate deep into the soil in search of water, and some have roots spreading widely near the surface to absorb rainwater quickly.

Adaptations in Plants of Snow-regions

Plants in snow-covered regions, such as conifers, have specific adaptations.

• Conical Shape: Many trees have a conical shape with sloping branches, which helps snow slide off easily, preventing accumulation and damage.
• Leaves: Leaves are typically needle-like, which reduces surface area and minimizes water loss and damage from freezing temperatures. They are also thick and waxy.

Adaptations in Forest Plants

Forests are rich in diversity, and plants here compete for sunlight.

• Height: Many trees grow tall to reach sunlight.
• Climbers and Vines: Smaller plants like climbers and vines grow on larger trees to get access to light.
• Spring-Loaded Seeds: Some plants have seeds that are dispersed with force, helping them spread.

Adaptations in Grassland Plants

Grasslands are dominated by grasses, with some shrubs and scattered trees.

• Fibrous Roots: Grasses have fibrous roots that prevent soil erosion.
• Drought Resistance: Many grassland plants are resistant to drought and can recover quickly after grazing or fires.

Adaptations in Animals

Adaptations in Animals of Snow-regions

Animals living in cold, snowy regions have adaptations to stay warm.

• Thick Fur/Skin: They often have thick fur or a layer of fat (blubber) to insulate their bodies. Examples include polar bears and yaks.
• White/Light Coloration: Their fur is often white or light-colored for camouflage in snow.

Adaptations in Desert Animals

Desert animals have developed ways to cope with extreme heat and water scarcity.

• Water Conservation: They may have thick skin to prevent water loss, or they excrete very little urine.
• Nocturnal Activity: Many are nocturnal, active during cooler nights to avoid the day's heat.
• Long Legs: Animals like camels have long legs to keep their bodies away from the hot sand.
• Fat Storage: Camels store fat in their hump, which can be metabolized to provide water and energy.

Adaptations in Grassland Animals

Grassland animals are adapted for speed and camouflage.

• Speed: Herbivores like deer and antelopes are fast runners to escape predators.
• Camouflage: Their body coloration often blends with the dry grass, providing camouflage.
• Strong Legs: Carnivores like tigers and lions also have strong legs and sharp claws for hunting.

Adaptations for Food

Animals show diverse adaptations related to their feeding habits.

• Herbivores: Have strong grinding teeth for plant material. Examples: Cow, deer.
• Carnivores: Possess sharp, pointed teeth and claws for tearing flesh. Examples: Lion, tiger.
• Omnivores: Have a combination of teeth for both plant and animal food. Examples: Humans, bears.
• Specialized Feeding: Some animals have highly specialized adaptations, like the long tongue of a chameleon for catching insects.

Classification of Living Organisms

Need for Classification

Classification is necessary to understand the vast diversity of life, study organisms systematically, and establish relationships between different groups.

Hierarchy of Classification

Scientists classify organisms into a hierarchical system, from broad categories to more specific ones.

1. Kingdom: The broadest category (e.g., Animalia, Plantae).
2. Phylum (animals) / Division (plants): A major grouping within a kingdom.
3. Class: Further division within a phylum/division.
4. Order: A grouping of related families.
5. Family: A grouping of related genera.
6. Genus: A grouping of closely related species.
7. Species: The most specific category, defining a group of organisms that can interbreed and produce fertile offspring.

This system was largely popularized by Carl Linnaeus, who is known as the "Father of Taxonomy".

Summary

• Organisms adapt to their environment through specific features and behaviors.
• Adaptations help organisms survive in diverse habitats like aquatic, desert, snow, forest, and grassland regions.
• Plants show adaptations in their leaves, stems, and roots to conserve water or survive cold.
• Animals adapt through body covering (fur, blubber), skin thickness, and behavioral patterns (nocturnal activity).
• Feeding habits also lead to specific adaptations in teeth and body structures.
• Classification is the scientific method of grouping organisms based on similarities and differences.
• The hierarchical system of classification includes Kingdom, Phylum/Division, Class, Order, Family, Genus, and Species.