Samacheer Class 6 Science - Living World of Animals

True
False – The geographical features and environmental conditions on earth do not remain the same from one place to another.
True
True
False – Paramecium is a unicellular organism.

The method by which birds catch their prey varies depending on the type of bird and the environment in which they live. Aquatic birds such as ducks, herons, and kingfishers use their specially adapted beaks to catch prey from water. These birds dive or wade into the water and use their beaks to catch fish and other aquatic organisms, often sliding them upside down into the water to secure their grip. Birds that inhabit paddy fields and wetlands, such as warblers and other insectivorous birds, use their sharp claws or talons on their limbs to grasp and catch small insects, worms, and other small creatures from plants and the ground. Some predatory birds like eagles and hawks have powerful talons that they use to snatch prey from the ground or water while flying. The specific hunting technique and body parts used depend on the bird's habitat, diet, and evolutionary adaptations to its environment.

Polar bears and penguins are both animals that live in extremely cold environments and have developed remarkable adaptive features to survive in these harsh conditions. Polar bears have several key adaptations for life in the Arctic. They possess short, sturdy limbs that help them navigate through snow and ice. Their body has a limited surface area relative to its volume, which helps reduce heat loss to the environment. They have thick skin that provides protection against the extreme cold climate. Beneath their skin lies a thick layer of fat or blubber that acts as an insulator, trapping body heat and maintaining their body temperature. Polar bears consume food rich in fat, particularly seal meat, which provides the energy and nutrients needed to sustain their large bodies in the cold. Penguins, which live in Antarctic regions, have equally impressive adaptations. They possess a boat-shaped or streamlined body that reduces water resistance and allows them to swim efficiently through water. Their feathers are densely packed and absorb sunlight, providing additional insulation. Like polar bears, penguins have thick skin and a substantial layer of fat beneath it that insulates them against the cold water and air. Their forelimbs are modified into short, flipper-like wings that are not suitable for flying in air but are perfectly adapted for swimming and paddling through water with great speed and agility.

Birds possess several remarkable features that enable them to fly in the air. The most fundamental feature is their streamlined body shape, which reduces air resistance and allows them to move efficiently through the air. The forelimbs of birds are modified into wings, which are the primary structures used for generating lift and propulsion during flight. These wings are covered with feathers that are specially designed to catch air and create the aerodynamic forces necessary for flight. Birds have hollow and light bones throughout their skeleton, which significantly reduces their overall body weight while maintaining structural strength. This lightweight skeletal structure is crucial for flight as it requires less muscular effort to lift and move the body through the air. The body of birds is completely covered with feathers, which not only provide insulation and waterproofing but also play a vital role in creating the aerodynamic surfaces needed for flight. Additionally, birds have powerful flight muscles, particularly the pectoral muscles, which provide the force needed to move their wings and sustain flight.

The camel possesses numerous remarkable adaptive features that enable it to thrive in the harsh desert environment. The long legs of the camel serve an important function by keeping its body elevated and away from the hot sand of the desert, reducing heat absorption from the ground and allowing air to circulate beneath the body for cooling. Camels have the remarkable ability to drink large quantities of water when it is available and store this water in their body tissues, allowing them to survive for extended periods without access to fresh water. To conserve water, camels produce only a small quantity of urine, which minimizes water loss from the body. The fat stored in the camel's hump can be broken down and metabolized for nourishment and energy when food is scarce in the desert. Camels have large, flat, padded feet that are specially adapted for walking on soft sand without sinking, distributing their weight evenly across the surface. The long eyelashes and thick hairs around the ears provide protection for these sensitive organs from the blowing dust and sand that is common in desert storms. Additionally, camels can close their nostrils to prevent dust and sand from entering their respiratory system, further protecting them from the harsh desert environment.

False – In unicellular organisms, the size of the cell increases as it grows
True
True
False – The forelimbs of birds are modified as wings.
True

Fishes possess numerous adaptive features that make them perfectly suited for life in aquatic environments. The head, trunk, and tail of a fish merge together to form a streamlined or fusiform shape, which reduces water resistance and allows the fish to move through water with minimal effort and maximum efficiency. Gills are special respiratory organs that are uniquely adapted to extract dissolved oxygen from water, allowing fish to breathe underwater. Most fishes have slippery scales covering their body, which protect the underlying tissues from injury and infection while also reducing friction with water. Fins are specialized structures that aid in swimming and maneuvering through water, with different types of fins serving different purposes such as movement, steering, and stability. The fish has a strong, muscular tail that acts as a rudder, enabling the fish to change direction and maintain balance in the water. The tail also provides the primary propulsive force for swimming. Additionally, many fish have a swim bladder, an internal gas-filled organ that helps them control their buoyancy and maintain their position at different depths in the water without expending excessive energy.