© Pelangi Publishing (Thailand) Co., Ltd. 2019 All rights reserved. No part of this publication may be reproduced, stored in any retrieval system or transmitted in any form or by any means without permission of Pelangi Publishing (Thailand) Co., Ltd. 2019
Title Page.indd 1
ISBN 978-616-541-312-1 First Published 2562
07/01/2019 18:07
Contents Chapter 1 Living Things and the Environment 1 A
Animal and plant adaptations............................ 2
B
Interdependence among living things................ 8
C
Interactions between living and non-living components....................................................... 16
D
Environmental protection................................... 22
Chapter 2 Heredity 29 A
Heredity ............................................................ 30
Chapter 3 Changes in Matter 48 A
Physical changes .............................................. 49
B
Chemical changes ............................................ 58
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Chapter 4 Forces 65 A
Resultant force .................................................. 66
B
Friction .............................................................. 72
Chapter 5 Sound 83 A
How does sound travel?.................................... 84
B
Pitch and loudness of sound ............................. 88
C
Noise ................................................................. 95
Chapter 6 Stars 102 A
Stars and planets .............................................. 103
B
Constellations.................................................... 106
Chapter 7 Water 123 A
Water sources ................................................... 124
B
Conservation of water ....................................... 130
C
Natural phenomena involving water ................. 132
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Let’s Find Out !
Special features
Encourages students to find information and present their findings.
in this book STEM Activity Provides an activity that engages in the application of knowledge of scientists, mathematicians and engineers.
K.W. L .W Allows students to know what to look for while reading and to reflect on what they have learned.
Let’s Scan and Watch !
Let’s Think! Challenges students with questions that promote higher thinking skills.
Provides direct access to the relevant information on the Internet by scanning the QR codes given.
Helps students to master their scientific knowledge and skills.
Presents a powerful diagram to literally ‘map’ out all the concepts in the chapter.
4C’s of the 21st Century 4C’s The Skills are:
Let’s Laugh ! Makes learning science a fun thing.
Communication Sharing thoughts, questions, ideas and solutions. Collaboration Working together to reach a goal. Putting talent, expertise smarts to work.
Let’s Know More ! Presents extra information that is relevant to the concept learned.
Critical Thinking Looking at problems in a new way and linking learning across subjects and disciplines.
Glossary
Creativity Trying new approaches to get things done equals innovation and invention.
Lists and explains difficult terms used in the text.
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Chapter
1
Living Things and the Environment Living things need food to survive. Look at the picture above. The grass makes its own food. The rabbit feeds on the grass. What feeds on the rabbit? Can you describe the relationship among these living things?
K.W. L .W What do I know about living things and the environment? 1. 2. 3.
K.W. L .W What else do I want to know about living things and the environment? 1. How do living things adapt to their habitats? 2. How do living things depend on other living things to survive? 3. How do living things interact with the non-living components? 4. How do we protect the environment? 5.
Living Things and the Environment
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Animal and plant adaptations
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Do organisms have different structures and characteristics to survive in their habitats?
1. Observe the animals above. 2. Where does the goldfish live?
3. What structures and characteristics does the goldfish have to survive in its habitat? List three.
4. Where does the tiger live?
5. What structures and characteristics does the tiger have to survive in its habitat? List three.
6. Observe the plants above.
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7. Where do the cacti live?
8. What structures and characteristics do the cacti have to survive in their habitat? List two.
9. Where do the mangrove trees live?
10. What structures and characteristics do the mangrove trees have to survive in their habitat? List two.
11. Do the organisms discussed above have the same structures and characteristics to survive in their habitats? Give a reason for your answer.
12. What is your conclusion for this activity?
There are different living things or organisms surviving in different habitats. Every organism has specialized structures and characteristics to help it to survive in its habitat. These specialized structures and characteristics are known as adaptations. Adaptations of animals and plants are important as poorly adapted organisms may not survive and reproduce. How do some plants adapt themselves to their habitats? Petioles
Water hyacinths are aquatic plants that float on the surface of ponds and lakes. Their leaf stalks or petioles are hollow and filled with air. This allows the plants to float, keeping the flowers and leaves above the water to prevent rotting.
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Mangrove trees live in swampy areas. They have prop roots. Prop roots provide support to the mangrove trees to grow on soft mud. The roots also help to take in air for the submerged roots to breathe in the oxygenpoor mud. Cacti live in deserts. Their leaves are reduced to spines to limit water loss. Their roots are long. They grow deep into the soil to absorb water. Cacti store water in their fleshy stems. Do you know why cacti have such adaptations? Pitcher plants are carnivorous plants that grow in nutrient-poor soil. How do they adapt? They have pitcher-shaped leaves. The leaves are slippery. There is nectar to attract insects into the pitchers. Once an insect falls into the pitcher, it will be digested. Conifers live in cold places. Their trees are cone-shaped to prevent snow from accumulating on them. Their needle-like or scale-like leaves have waxy cuticles to prevent water loss.
Let’s Think ! What structures and characteristics do that plants living in the tropical rainforest have?
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Animals also have special structures and characteristics which help them to survive in their habitats. Let us look at these examples. Camels are adapted to live in deserts. A camel has large and flat feet to walk on the sand easily. Its legs are long to keep its body away from the hot sand. It has long eyelashes to keep sand out of its eyes. It stores fat as food in its hump. It uses the fat when food and water are not available.
Fish are adapted to live in the water. Fish have fins to swim in the water. They also have streamlined body to help them swim smoothly in the water. Gills help them to take in the dissolved oxygen in the water.
Frogs live on land and water. On land, frogs can breathe through their lungs. They have strong hind legs for leaping on land. In water, they can breathe with their moist skin. Their webbed feet help them to swim in the water.
Birds
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characteristics which help them to fly in the air. Their forelimbs are modified into wings for flying. They also have feathers and streamlined bodies to help them fly. Their bones are hollow to make their bodies light.
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Monkeys are adapted to live on trees. They have strong and long limbs which enable them to move and swing from tree to tree. They also have hooklike hands and flexible feet to hold on to tree trunks and branches. Some monkeys have prehensile tails that can be used to grip branches and food.
Polar regions like Arctic are habitats to polar bears. Polar bears have thick fur and thick layers of fat under the skin to keep their bodies warm. Their wide feet help them to walk on snow and ice and to swim in water. What would happen to the polar bears if they were to live in a dry and hot habitat like the desert?
Let’s Find Out ! Look at the animals shown below. Where do they live? What are the special structures and characteristics that help these animals to survive in their habitats? Discuss in groups. Present the findings of your group in the class.
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How do animals protect themselves from enemies? Many animals match their environment in colors or shapes. This makes them difficult to be seen and helps them escape from their enemies or creep on their prey. This is called camouflage. For example, some animals that live in snowy areas are white. Some animals that live on trees are green and some animals that live in the soil are soil-colored.
Arctic fox
Caterpillar
Rattlesnake
An octopus can change the texture and color of its skin to match its surroundings.
Shapes can also help to camouflage an animal. For example, a walking stick is shaped like twigs and a leaf insect looks like leaves. They blend well with their habitats.
Walking stick
Leaf insect
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B
Interdependence among living things
Organisms like plants and algae have chlorophyll to absorb sunlight. They can carry out photosynthesis to make their own food. They are called producers. Animals cannot make their own food. They have to feed on plants or other organisms. They are called consumers. We can categorize the consumers according to what they eat. Herbivores are animals that eat plants only.
Examples of herbivores
Carnivores are animals that eat other animals only.
Examples of carnivores
Omnivores eat both plants and other animals.
Examples of omnivores
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A food chain shows the feeding relationship between the producers and the consumers. A food chain always starts with a producer. For example, the grass (producer) is eaten by a zebra (herbivore). The zebra is eaten by a lion (carnivore). This relationship can be illustrated by a simple food chain as shown below.
Grass
Zebra
Lion
The arrow in a food chain means ‘it is eaten by’. Look at the food chain below. It is a food chain found in a paddy field. This food chain means the rat eats the rice plant. The snake eats the rat while the eagle eats the snake.
Rice plant
Rat
Snake
Eagle
The following is an example of a food chain in a forest. Can you explain the food chain?
Grass
Rabbit
Tiger
Example of a food chain in a forest
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Can food chains be interconnected? 1. Make a food chain with these organisms: Grasshopper Frog Eagle Grass
2. Make a food chain with these organisms: Rabbit Eagle Grass
3. Can you combine the two food chains into one with each animal appearing once only? Draw it in the space below.
4. Can food chains be interconnected?
5. Based on what you have drawn, explain why food chains can be interconnected?
6. What is your conclusion for this activity?
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