homework encyclopedia

The largest organ in the nervous system is the brain. It controls vital involuntary processes, such as breathing, as well as our ...

140 Human Body Our eyes create the sense of vision. They take in light rays, focus them to create an image, and convert this ima ...

Human Body^141 HOW DO EARS HELP US BALANCE? The semi-circular canals contain fluid that moves whenever the head moves, making ti ...

Food enters the body through the mouth. The mouth is the first part of the digestive system, where food is mashed and moistened ...

Human Body^143 The main entrance to the body’s airways is the nose. It also contains our smell sensors. The outer part of the no ...

144 Human Body The process of breaking down food into molecules the body can absorb is called digestion. The digestive system be ...

Human Body^145 WHICH ORGANS MAKE DIGESTIVE ENZYMES? The salivary glands, stomach, pancreas, and small intestine all produce dige ...

146 Human Body A vital organ, the liver carries out hundreds of essential chemical processes, adjusts the levels of many substan ...

Human Body^147 HOW DO HORMONES WORK? Hormone molecules travel in the blood looking for specific cells which they bind on to. Thi ...

148 Human Body FIND OUT MORE. Cells 73 • Genetic Engineering 210–211 • Genetics 209 HOW DO GENES AFFECT CHARACTERISTICS? Genes d ...

Human Body^149 FIND OUT MORE. Hormones 147 • Skeleton 130–131 • Skin 133 • Teeth 143 It takes nine months for an embryo to grow ...

WHAT ARE THE MAJOR HEALTH ISSUES IN THE WORLD TODAY? In poor countries, dirty water and lack of adequate food are among the main ...

WHAT ARE BACTERIA AND VIRUSES? The most common infectious diseases are caused by bacteria and viruses. Bacteria are single-celle ...

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SCIENCE 154 TECHNOLOGY 154 MEASUREMENTS 155 MATHEMATICS 155 MATTER 156 ATOMS 157 TIME 158 QUANTUM THEORY 159 ELEMENTS 160 CHEMIS ...

154 Science and Technology FIND OUT MORE. Computers 190 • Design 326 • Machines 196–197 What makes the stars shine? Why is the s ...

Science and Technology^155 FIND OUT MORE. Physics 163 Mathematics explores the properties (characteristics) of numbers, shapes, ...

FIND OUT MORE. Atoms 157 • Energy 166 • Forces 164 • Heat 168–169 • Motion 165 • Universe 26 Dust, living things, oceans, mounta ...

FIND OUT MORE. Electricity 182 • Elements 160–161 • Nuclear Energy 167 Science and Technology^157 All matter is made from partic ...

FIND OUT MORE. Light 178–179 • Quantum Theory 159 • Space 10 • Universe 26 158 Science and Technology HOW DO WE MEASURE TIME? Th ...