Cambridge Primary Stage 4 Science Notes – Ecosystems

SMART EXAM RESOURCES

CAMBRIDGE PRIMARY STAGE-4

SUBJECT: SCIENCE [ BIOLOGY]

TOPIC: ECOSYSTEMS

🌍 Types of Habitats and Their Conditions

• Habitat:A habitat is the natural home of a plant or animal — where it lives, grows, and finds food, water, air, and shelter.

Each habitat has its own conditions such as temperature, water, light, and type of soil.

Types of Habitats:

• Desert Habitat

• Rainforest Habitat

• Grassland

• Forest

• Polar

• Mountainous

• Marine (Ocean)

• Freshwater

• Urban

Desert Habitat:🌍 Description

• A desert is a very dry and hot habitat that receives very little rainfall throughout the year — usually less than 25 cm of rain annually.

• Deserts cover about one-fifth of the Earth’s surface and can be found on every continent.

• Some are hot deserts (like the Sahara), while others are cold deserts (like the Gobi).

🌡️ Climate Conditions

• ☀️ Temperature: Extremely hot during the day (up to 50 °C) but very cold at night (can fall below 0 °C).

• 💧 Rainfall: Very low; rain may fall only once or twice a year.

• 🌫️ Air: Very dry (low humidity).🌬️ Winds: Often strong and dusty.🏖️ Soil: Sandy or rocky, poor in nutrients, and does not hold water well.

🌱 Plant Life and Adaptations

Plants that live in deserts are called xerophytes — they are specially adapted to survive with little water.

Rainforest:

🌴 Rainforest Habitat

🌍 Description

A rainforest is a dense forest with lots of trees, plants, and animals, found in regions that get heavy rainfall all year round.Most rainforests are located near the equator, such as the Amazon (South America), Congo (Africa), and Southeast Asia.

🌦️ Climate Conditions

• 🌧️ Rainfall: Very high — over 200 cm per year, often raining almost daily.

• 🌡️ Temperature: Warm and stable — around 25–30 °C all year (no seasons).

• 💧 Humidity: Very high (can be 80%–90%).

• ☀️ Sunlight: Limited at ground level due to thick canopy layers.

• 🍃 Air: Moist and still (not very windy).

🌱 Plant Life and Adaptations

Rainforests have four layers of vegetation: emergent, canopy, understory, and forest floor.Plants are adapted to soak up sunlight, shed water, and grow quickly in competition for light.

🌾 Summary

Rainforests are warm, wet, and full of life, with the highest number of plant and animal species on Earth.Plants have amazing adaptations to:

• Climb for sunlight,

• Get rid of extra water,

• And grow in the shady forest floor.

Grassland:

🌍 Description

A grassland is a wide, open area covered mainly with grasses and very few trees.Grasslands are found on every continent except Antarctica — examples include the Savannas of Africa, the Prairies of North America, and the Steppes of Asia.They are home to many large grazing animals and fast predators.

🌦️ Climate Conditions

• 🌞 Temperature: Warm to hot in summer and cool in winter (usually between 20 °C – 30 °C).

• 🌧️ Rainfall: Moderate — about 25 cm to 75 cm per year (less than forests but more than deserts).

• 🌬️ Wind: Often strong, blowing across open plains.

• 🍂 Soil: Fertile and rich in nutrients, supporting grass growth.

• 🔥 Fire: Natural grassland fires may occur during dry seasons and help new grass grow.

🌱 Plant Life and Adaptations

Plants in grasslands must survive strong winds, occasional drought, and grazing animals.Most have deep roots to absorb water and regrow quickly after being eaten or burnt.

🦁 Animal Life and Adaptations (Quick Notes)

Though plants dominate, grasslands also support:

• Lions, cheetahs, and wolves – fast runners to chase prey.

• Zebras, antelopes, and buffaloes – graze on grasses and migrate for food.

• Burrowing animals like meerkats and prairie dogs – hide from predators and heat.

🌾 Summary

Grasslands have moderate rainfall, fertile soil, and are mostly covered by tough grasses.Plants are adapted to:

• Store water in roots,

• Survive fire and grazing, and

• Regrow quickly when conditions improve.

Forest: (Temperate):

🌳 Temperate Forest Habitat

🌍 Description

A temperate forest is a habitat with many trees, shrubs, and animals, found in regions that have four distinct seasons — spring, summer, autumn, and winter.These forests grow in parts of North America, Europe, and Asia, where the climate is neither too hot nor too cold.They are made up mostly of deciduous trees (that lose their leaves in winter) and sometimes evergreen trees (that keep their leaves all year).

🌦️ Climate Conditions

• 🌡️ Temperature: Warm summers (around 20 °C–25 °C) and cold winters (can drop below 0 °C).

• 🌧️ Rainfall: Moderate to high — between 75 cm and 150 cm per year, spread through the seasons.

• 🍂 Seasons: Four distinct seasons — trees lose leaves in autumn and grow new ones in spring.

• 💨 Air: Moist and cool, with regular rainfall and some snow in winter.

• 🌳 Soil: Rich in nutrients from fallen, decomposed leaves.

🌱 Plant Life and Adaptations

Plants in temperate forests must survive seasonal changes in temperature and light.Most trees lose their leaves to save water in winter and grow new ones in spring when conditions improve.

🦉 Animal Life and Adaptations (Quick Notes)

Animals must cope with changing seasons and temperatures.Common examples include:

• Bears – hibernate in winter when food is scarce.

• Deer – grow thick fur for cold months, shed it in spring.

• Owls & foxes – blend with brown forest floor (camouflage).

• Squirrels – store nuts to eat in winter.

🌳 Summary

Temperate forests have mild to cold climates, rich soil, and seasonal changes.Plants are adapted to:

• Lose leaves in winter to conserve water,

• Regrow quickly in spring, and

• Survive freezing temperatures with thick bark or evergreen needles

Polar ( Arctic) Region:

❄️ Arctic (Polar) Habitat

🌍 Description

The Arctic region (around the North Pole) and the Antarctic region (around the South Pole) are called polar habitats.They are the coldest places on Earth, covered with ice and snow most of the year.The sunlight is very limited — during winter, the Sun does not rise for weeks, and in summer, it may not set for months.Only a few specially adapted plants and animals can survive here.

🌦️ Climate Conditions

• 🌡️ Temperature: Extremely cold — often below –30 °C in winter; rarely above 10 °C in summer.

• 🌨️ Precipitation: Very little rainfall; most precipitation falls as snow.

• 💨 Wind: Strong, icy winds are common.

• 🌫️ Light: Long dark winters (polar night) and long bright summers (midnight sun).

• ❄️ Soil: Frozen most of the year — called permafrost.

• 🌬️ Air: Very dry (like a cold desert).

🌱 Plant Life and Adaptations

Because of the extreme cold, only hardy, low-growing plants can survive.They grow during the short summer when sunlight returns.

🐻‍❄️ Animal Life and Adaptations

Animals in the Arctic have thick fur, fat layers, and special behaviours to survive freezing temperatures.

🌨️ Summary

The Arctic (Polar) region is freezing cold, windy, and icy, with long winters and short summers.Only a few plants and animals can survive here, and they are adapted to:

• Keep warm with fur or blubber,

• Stay camouflaged in snow, and

• Grow or feed quickly during the short summer.

Mountainous Region:

⛰️ Mountain (Mountainous) Habitat

🌍 Description

A mountain habitat is found in high-altitude regions where the land rises sharply above the surrounding area.Examples include the Himalayas, Andes, Rocky Mountains, and Alps.As you climb higher up a mountain, the temperature drops, air becomes thinner, and winds become stronger.These harsh conditions mean only specially adapted plants and animals can live there.

🌦️ Climate Conditions

• 🌡️ Temperature: Decreases with height — warm at the base, freezing cold at the top.

• ❄️ Snow: Common on high peaks, often covered year-round.

• 💨 Wind: Strong, cold, and dry at high altitudes.

• 🌧️ Rainfall: More rainfall on lower slopes, less at higher levels.

• 🌫️ Air: Thin, with less oxygen as altitude increases.

• 🌳 Seasons: Short growing season due to cold climate.

🌱 Plant Life and Adaptations

Plants at high altitudes must withstand cold, wind, and poor soil.They tend to be short, tough, and slow-growing.

🐐 Animal Life and Adaptations

Animals in mountain regions are adapted to cold temperatures, thin air, and steep slopes.

🏔️ Summary

Mountain habitats have cold, windy weather and steep, rocky slopes.Plants and animals are adapted to:

• Survive low temperatures and thin air,

• Resist strong winds, and

• Climb or grow on steep, uneven ground.

Marine Habitat : (Ocean )

🌊 Ocean (Marine) Habitat

🌍 Description

The ocean habitat covers nearly three-quarters of the Earth’s surface and includes seas, oceans, and coral reefs.It is a saltwater environment that supports a wide variety of life — from tiny plankton to the largest animal on Earth, the blue whale.The ocean has different zones, from the sunlit surface to the dark deep ocean floor, each with different living conditions.

🌦️ Climate Conditions

• 💧 Water Type: Salty (contains dissolved salts and minerals).

• 🌡️ Temperature: Warm near the equator and surface; very cold in deep or polar areas.

• 🌞 Light: Only the top layer (called the sunlit zone) receives sunlight; deep areas are dark.

• 🌫️ Pressure: Increases with depth — deeper areas have very high water pressure.

• 🌬️ Currents: Ocean currents and tides move water and nutrients around the globe.

• 🪸 Oxygen: More near the surface where waves mix air with water.

🌱 Plant Life and Adaptations

Plants and plant-like organisms in oceans must float, anchor to rocks, or absorb nutrients directly from water since there is no soil.

🐠 Animal Life and Adaptations

Animals in oceans have special features to breathe, move, and survive underwater.

🌊 Summary

The ocean is a vast, salty habitat with zones of light and darkness, warmth and cold, and high pressure in the depths.Marine plants and animals are adapted to:

• Live without soil,

• Survive pressure and movement of water, and

• Find or make food in a watery world.

Freshwater:

💧 Freshwater Habitat

🌍 Description

A freshwater habitat is any body of water that has little or no salt.Examples include rivers, lakes, ponds, and streams.These habitats support many plants and animals that cannot live in salty water like the ocean.

🌦️ Climate Conditions

• 💧 Water Type: Non-salty; contains minerals and oxygen.

• 🌡️ Temperature: Changes with season and depth — warm at surface, cooler below.

• 🌤️ Light: Sunlight reaches shallow waters easily, helping plants grow.

• 🌫️ Flow: Can be still (lakes, ponds) or moving (rivers, streams).

• 🌬️ Air & Oxygen: Dissolved oxygen from wind and water movement supports aquatic life.

• 🪸 Soil: Muddy or sandy bottom with nutrients for plants.

🌱 Plant Life and Adaptations

Plants in freshwater must survive underwater, floating, or along wet edges where roots may be in mud.

🐸 Animal Life and Adaptations

Animals in freshwater habitats are adapted to live, swim, or feed in or near water.

🌾 Summary

Freshwater habitats are non-salty environments like rivers, lakes, and ponds.Plants and animals here are adapted to:

• Float or anchor in water,

• Absorb oxygen and sunlight, and

• Survive both wet and dry conditions near the shore.

Urban:

🏙️ Urban Habitat

🌍 Description

An urban habitat is a place where humans live and build cities or towns.It includes buildings, roads, gardens, parks, drains, and houses.Although it is created by people, many plants and animals adapt to live alongside humans — finding food, water, and shelter in this environment.

🌦️ Climate Conditions

• 🌡️ Temperature: Usually warmer than nearby rural areas because buildings and roads absorb heat (called the urban heat effect).

• 🌧️ Rainfall: Variable — often more rainfall due to heat rising from buildings.

• 💨 Air: Can be polluted from vehicles and factories.

• 🌳 Vegetation: Limited — only in parks, gardens, and along roads.

• 💡 Light & Noise: High light and sound levels (artificial environment).

• 💧 Water Sources: Mostly through drains, ponds, fountains, and water storage systems.

🌱 Plant Life and Adaptations

Plants in cities must survive pollution, limited space, and poor soil.They often grow in parks, cracks in pavements, walls, and gardens.

🐀 Animal Life and Adaptations

Animals in cities adjust to living near humans, finding food in dustbins, gardens, or drains.They are often nocturnal, fast-moving, and not easily scared.

🌆 Summary

Urban habitats are man-made environments full of buildings, lights, and people.Plants and animals here are adapted to:

• Survive pollution and heat,

• Find food and shelter among humans, and

• Live in small, crowded spaces with little natural soil or water.

In a nutshell:

🏞️ Major Habitats and Their Conditions

🗣️ Words Used to Describe Habitat Conditions

Sample Solutions to Past Exam Paper Questions:

1.

✅ Answer: The food chain belongs to an ocean habitat

🟤 Explanation:

The food chain includes algae, fish, squid, and shark — all of which live in the ocean (marine) habitat.

• Algae float or grow near the ocean surface.

• Fish eat the algae.

• Squid and shark are marine animals found in deeper ocean waters.

So the food chain belongs to an ocean habitat. 🌊

2.

✅ Answer:The colour of the toad makes it suited to living in its habitat because it is camouflaged.

🟤 Explanation:

The toad’s brownish, speckled colour helps it blend in with the ground, making it hard for predators to see.This camouflage keeps the toad safe from being eaten while it lives on the ground.

3.

✅ Answer:they sometimes flap to keep cool

🐘 Explanation:

Elephants live in hot countries, and their large ears help them lose heat.When elephants flap their ears, blood flowing through the ear veins cools down — helping the elephant’s whole body stay cool.

🎯 Exam Tips:

• To master this topic, you need to have an idea about habitats in which the different animals live as well as their special adaptations, if any.