Class 7 Notes

Class 7 Science Notes Chapter 7 (Chapter 7) – Examplar Problems Book

Philoid

Philoid

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Examplar Problems
Detailed Notes with MCQs of Chapter 7: Weather, Climate and Adaptations of Animals to Climate from your Science Exemplar book. This chapter is crucial not just for your school exams but also forms a base for questions in various government exams. Pay close attention to the definitions and especially the examples of adaptations.

Chapter 7: Weather, Climate and Adaptations of Animals to Climate - Detailed Notes

1. Weather

  • Definition: Weather refers to the day-to-day condition of the atmosphere at a specific place with respect to elements like temperature, humidity, rainfall, wind speed, etc.
  • Key Characteristics:
    • It is a short-term phenomenon.
    • It can change frequently, sometimes even within a day (e.g., sunny morning, rainy afternoon).
    • It is complex and can be difficult to predict accurately over longer periods.
  • Elements of Weather:
    • Temperature: Degree of hotness or coldness. Measured using a maximum-minimum thermometer.
    • Humidity: Amount of water vapour present in the air. High humidity makes us feel sweaty. Measured using a hygrometer.
    • Rainfall: Precipitation in the form of water droplets. Measured using a rain gauge (a measuring cylinder with a funnel).
    • Wind Speed: Speed at which air is moving. Measured using an anemometer.
  • Source of Weather Changes: The Sun is the primary source of energy that causes changes in the weather. Energy absorbed and reflected by the Earth's surface, oceans, and atmosphere drives wind patterns, evaporation, and temperature changes.
  • Weather Reports: These are prepared by the Meteorological Department of the government. They collect data on various weather elements and use it to predict the weather. Reports usually contain information about the past 24 hours' temperature, humidity, rainfall, and predictions for the current day.

2. Climate

  • Definition: Climate is the average weather pattern taken over a long period of time, typically 25 years or more, for a particular place.
  • Key Characteristics:
    • It represents long-term atmospheric behaviour.
    • It is more stable and predictable than weather.
  • Difference between Weather and Climate:
    • Weather: Short-term, changes frequently, describes conditions now or over a day/week.
    • Climate: Long-term average, relatively stable, describes typical conditions over years/decades.
  • Factors Determining Climate: While many factors exist, for this level, focus on long-term patterns of temperature and rainfall.
  • Examples of Climatic Zones (based on temperature & rainfall):
    • Polar Regions: Extremely cold for most of the year, heavy snowfall.
    • Temperate Regions: Moderate temperatures and rainfall (not extreme heat or cold).
    • Tropical Regions: Generally hot (high temperatures), can be very wet (rainforests) or dry (deserts).
    • Desert Climate (Hot & Dry): High temperatures, very little rainfall (e.g., Rajasthan).
    • Tropical Rainforest Climate (Hot & Wet): High temperatures and heavy rainfall throughout the year (e.g., North-East India, Western Ghats).

3. Climate and Adaptations of Animals

  • Adaptation: The process by which organisms develop certain features (physical characteristics) or habits (behaviours) that help them survive successfully in their specific habitat and climate. Adaptations occur over long evolutionary periods.

  • A. Adaptations to Polar Regions (e.g., Arctic, Antarctic)

    • Climate: Extremely cold, snow-covered, long periods of darkness/daylight depending on the season.
    • Key Animals: Polar bears, penguins, seals, arctic foxes, reindeer, musk oxen, Siberian cranes (migratory).
    • Polar Bear Adaptations:
      • White Fur: Camouflage against snow (helps in hunting and avoiding predators); traps air for insulation.
      • Two Thick Layers of Fur: Excellent insulation against extreme cold.
      • Layer of Fat (Blubber): Insulates the body, provides energy reserve.
      • Wide, Large Paws: Help in walking on snow (like snowshoes) and swimming.
      • Sharp Claws: Grip on ice.
      • Strong Sense of Smell: Locate prey (like seals) from far away.
      • Ability to Close Nostrils: Allows them to remain underwater while swimming.
    • Penguin Adaptations:
      • Thick Skin & Blubber: Insulation against cold.
      • White Front, Black Back (Countershading): Camouflage in water (merge with light from above, darkness from below).
      • Huddling Behaviour: Penguins crowd together in large groups to keep warm.
      • Streamlined Body & Webbed Feet: Makes them excellent swimmers. Wings modified into flippers.
    • Migration: Some birds (like the Siberian Crane) migrate from polar regions to warmer areas (like Bharatpur in Rajasthan, Sultanpur in Haryana, India) during harsh winters to escape the cold and find food.

  • B. Adaptations to Tropical Rainforests

    • Climate: Hot and humid throughout the year, abundant rainfall, supports huge biodiversity.
    • Location: Found near the equator. In India: Western Ghats, Assam.
    • Challenges: Intense competition for food and space due to the large number of species.
    • General Adaptations: Many animals are adapted to live on trees. Development of sensitive hearing, sharp eyesight, skin colour for camouflage, specific diets to reduce competition.
    • Red-Eyed Frog: Develops sticky pads on its feet to help it climb trees easily.
    • Monkeys: Possess long tails for grasping branches (prehensile tails in some); hands and feet adapted for holding onto branches.
    • Toucan: Has a long, large beak which helps it reach fruits on branches that might be too weak to support its weight. Also helps in accessing different types of food.
    • Big Cats (Lions, Tigers): Have thick skin, sensitive hearing, sharp eyesight, and skin colour (e.g., yellow-brown for lions, stripes for tigers) that helps them camouflage while hunting.
    • Lion-Tailed Macaque (Beard Ape):
      • Found in the rainforests of the Western Ghats in India.
      • Most distinctive feature: Silver-white mane surrounding its head.
      • Excellent climber, spends most of its life on trees (arboreal).
      • Feeds mainly on fruits, seeds, young leaves, stems, flowers, buds, and sometimes insects found under the bark.
    • Elephant (Adapted to Indian Rainforests):
      • Trunk: Used as a nose (strong sense of smell), for picking up food, and for sucking water to drink or spray on the body.
      • Tusks (Modified Teeth): Used to tear bark from trees (food), dig for roots, and for defence/fighting.
      • Large Ears: Help to hear even very soft sounds; also have a large surface area with blood vessels close to the skin, helping the elephant radiate heat and keep cool in the hot, humid climate.
      • Large, Padded Feet: Support heavy weight and allow quiet movement.

Multiple Choice Questions (MCQs) for Practice

  1. Which instrument is used to measure the amount of rainfall?
    (a) Thermometer
    (b) Anemometer
    (c) Rain gauge
    (d) Hygrometer

  2. The average weather pattern taken over a long time, say 25 years, is called the ______ of the place.
    (a) Climate
    (b) Weather
    (c) Adaptation
    (d) Humidity

  3. Which of the following is NOT an element of weather?
    (a) Temperature
    (b) Humidity
    (c) Altitude
    (d) Wind speed

  4. The white fur of a polar bear helps it in:
    (a) Absorbing sunlight to keep warm
    (b) Camouflaging against the snow and insulating from cold
    (c) Swimming faster in water
    (d) Finding mates easily

  5. Penguins huddle together primarily to:
    (a) Protect themselves from predators
    (b) Keep themselves warm
    (c) Help digest their food
    (d) Attract mates

  6. Tropical rainforests are characterized by:
    (a) Low temperature and heavy rainfall
    (b) High temperature and low rainfall
    (c) Hot and humid conditions with plentiful rainfall
    (d) Extreme cold and snowfall

  7. The Lion-tailed Macaque is predominantly found in which region of India?
    (a) Himalayan Region
    (b) Deserts of Rajasthan
    (c) Western Ghats
    (d) Sunderbans Delta

  8. The long, large beak of a Toucan is an adaptation that helps it to:
    (a) Fight predators
    (b) Build nests
    (c) Reach fruits on weak branches
    (d) Dig for insects in the ground

  9. Which adaptation helps elephants keep cool in the hot and humid climate of tropical rainforests?
    (a) Thick skin
    (b) Large ears
    (c) Strong trunk
    (d) Tusks

  10. The primary source of energy that causes changes in weather is:
    (a) The Moon
    (b) Wind
    (c) Ocean currents
    (d) The Sun

Answer Key:

  1. (c)
  2. (a)
  3. (c)
  4. (b)
  5. (b)
  6. (c)
  7. (c)
  8. (c)
  9. (b)
  10. (d)

Remember to revise these concepts thoroughly. Understanding the difference between weather and climate, and memorizing the specific adaptations of animals to polar and tropical regions, is key for scoring well. Good luck with your preparation!

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