7th std Topic -1 Living world adaptation and their classification part-1,2,3,4,5.

Gradual changes occur in the body parts and also in the behaviour of organisms which
help them to adjust to their surroundings. Such changes are called adaptations. They take place over a long period of time.

The Living World : Adaptations and Classification

#Adaptation in aquatic plants : Some of the aquatic plants are firmly rooted in the soil at the bottom of the water bodies. Their stems are submerged, while leaves and flowers float on the surface. However, some plants are entirely afloat. Their roots are not anchored in the soil. leaves and flowers float on the surface. However, some plants are entirely afloat. Their roots are not anchored in the soil. The surfaces of leaves and stems of many aquatic plants The surfaces of leaves and stems of many aquatic plants are covered with a waxy layer. Leaves of some aquatic plants are covered with a waxy layer. Leaves of some aquatic plants are thin and slender like a ribbon. This shape helps them

1.2 Aquatic plants Use your brain power ! 1. 2. 3. Why does water trickle off lotus leaves ? Why don’t the leaves of these plants rot in water ? Why are their roots short and fibrous ?

#Adaptation in #desert plants : Try this. to withstand fast currents of water. Air spaces in stems and petioles of aquatic plants are useful for floating in water. Desert plants are either leafless or their leaves are like small needles or have been As a result, they lose very little water by evaporation. The stem stores water and food and is therefore fleshy. The stems are green as they perform photosynthesis in the absence of leaves. Their roots penetrate deep into the soil and some roots spread away into the soil in search of water. There is a thick layer of a waxy substance on the stems of these plants,

#Adaptation in plants of snowy regions: Can you tell ? In what way are sloping branches useful to plants in a snowy region ? Plants of snowy regions mainly include conifers like deodar and pine. These trees are conical in shape due to their sloping branches. In the heavy snowfall and extreme cold in these regions, their conical shape prevents the snow from accumulating on the tree and the thick bark helps the tree to withstand the cold

#Adaptation in plants of forest: regions A variety of plants – trees, shrubs and herbs – are found in forests. These plants compete amongst themselves for sunlight. Hence, trees grow tall to get sunlight and climbers and vines grow to a great height with the support of trees. Spring-like tendrils on the stems of some climbers is an example of adaptation.

#Adaptation in grassland plants : Forest Diverse types of bushes and grasses are found in the grasslands. Fibrous roots of grasses prevent soil erosion. Forests in the equatorial region are dense. Animals like tiger, elephants and deer can remain hidden in these grasses. However, grasses in cold regions are very short. Animals like the rabbit are found in such grasses. Vast meadows are found in hilly areas as well as plains

Adaptation in #desert_animals Deserts are characterized by severe scarcity of water. Hence, desert animals have a thick skin to prevent loss of water from the body. Their legs are long with flat and cushioned soles. The nostrils are protected by folds of skin. The eyelashes are long and thick. Rats, snakes, spiders, lizards in deserts live in deep burrows during daytime and are active at night

Adaptation in animals of #snowy regions From the internet, download images of animals like yak, polar bear, white fox, silver fox, mountain goat, Siberian husky dog and snow leopard. Compare these images with those of similar animals from tropical forests. A white or silver body colour, long, thick hair on the skin are typical characteristics of animals of snowy region. How are these useful to them ? Adaptation in #aerial animals What is the main difference between vehicles on the road and aeroplanes ? The spindle-shaped body of birds also minimises the resistance of air while flying. With hollow bones, a body covering of feathers and modification of forelegs into wings, their body is light in weight and adapted for flying. The body of insects also is light in weight and tapers at both ends. They can fly with two pairs of wings and also walk with six stick-like legs. Bats can fly with the help of the patagium, a thin fold of skin between their forelegs and hind legs. Observe the various birds and insects in your area.

Adaptation in #reptiles Observe, from a distance, how snakes and earthworms creep. Which organs do they use for creeping ? Are there any special changes for that purpose? Note any such changes. Animals like house lizard, garden lizard, crocodile use their muscles for creeping. Similarly, they show adaptations in skin, soles of feet, body colour, etc. For example, the house lizard and monitor lizards have clawed toes and thin soles, whereas snakes have scaly skin. Wings

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