'This Grade 8 Natural Sciences Noteset contains comprehensive summaries of all topics covered in the syllabus during Term 1 to 4. It is a must-have for any student looking to excel in their Grade 8 Natural Sciences exam. These notes are perfect for revision, helping students to quickly and accurate...
, Photosynthesis & Respiration
ENERGY > SUSTAINING LIFE:
→ energy need (to sustain life) = drives the interactions in ecosystems
All living things need energy for life processes:
Z Movement
Z Growth
Z Stay warm
[Sun = source of energy in ecosystems]
Z Light
Z Heat
[Plants = capture light energy > photosynthesis]
PHOTOSYNTHESIS:
→ chemical process during which plants glucose from carbon dioxide (from the air) and
water (from the ground) by using energy from the Sun;
[BYPRODUCT / BYPRODUCT = oxygen]
[Chlorophyll →green matter in plants that absorbs/captures the energy of sunlight]
GLUCOSE:
→ sugar > simplest form of food
→ Plants turn glucose into starch, cellulose and other chemical compounds [required for
growth and reproduction]
➢ Food's energy content is measured in kilojoules (kJ) OR kilocalories (kCal)
➢ The energy stored in food can be measured by burning a small amount of food in an
instrument called a calorimeter.
[Glucose = broken down → energy is used → used for bodily processes
[RESPIRATION]]
[RESPIRATION →process by which energy is released from glucose during
a series of chemical reactions]
RESPIRATION & BREATHING:
DIFFERENT WAYS OF BREATHING:
➢ Fish → gills
➢ Whales → holes on top of head
➢ Caterpillars → holes against body
➢ People → nasal cavities (air goes to lungs)
QUIIIIZZZZ!!!
WHY DO YOU BREATHE HARDER WHEN YOU EXERCISE?
➢ Respiration takes place in every cell of your body.
➢ When you jog or do exercises you need more energy.
➢ This means that respiration takes place faster and that you therefore need more
oxygen than usual.
➢ Your body automatically responds to the need for more oxygen by breathing
harder and faster.
[ECOLOGY → branch of the sciences that studies the interaction of
organisms with other organisms and their environment]
Ecologist > Person who studies these relationships and interactions
4 LEVELS > STUDY OF ECOLOGY:
→ group of organisms of the same species that are found in a
POPULATION specific area at a specific time and they must be able to breed in
that area
[population growth & factors affecting population growth or decline]
→all the populations of organisms that interact in a specific area
COMMUNITY [2 OR MORE POPULATIONS]
→communities' interaction with the non-living things in their
ECOSYSTEM environment
[community + habitat]
→all the ecosystems on Earth combine to form the biosphere
BIOSPHERE
ECOSYSTEMS > BIOTIC & ABIOTIC COMPONENTS:
BIOTIC ABIOTIC
[LIVE] [NON-LIVING]
Z Plants Z Temperature
Z Animals Z Sunlight
Z People Z Water
Z Wind
Z Sand
SURVEY METHODS > SIZE OF ECOSYSTEM:
SQUARE SURVEYS CROSS SECTION SAMPLING
→a square or grid for surveys →a line through the study area for sampling
[PLANTS / SLOW MOVING ANIMALS] [STATES OF ABIOTIC FACTORS
CHANGE]
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