GoalReview blood and kidneys, photosynthesis, water in plants and food chains with new questions.
New words
kidney · an organ that filters wastes and extra water from the bloodphotosynthesis · how green plants make food from carbon dioxide and water using sunlightproducer · a living thing that makes its own food and starts a food chain
Explanation
Another set of ideas. Blood carries oxygen and nutrients to every part of the body and brings back carbon dioxide and wastes. The heart is a pump with two sides: one sends blood to the lungs and the other to the rest of the body. The two kidneys filter wastes and extra water from the blood to make urine, which is stored in the bladder. In plants, leaves use sunlight, carbon dioxide and water to make food and give out oxygen: this is photosynthesis. Roots take in water that travels up the stem, and the leaves let water vapour out through small pores: transpiration. A food chain begins with a producer, a plant. Arrows point from the food to the eater, and every link depends on the one before. People are part of food chains too.
sunlight + carbon dioxide + water→leaf makes food→sugar and oxygen
Worked examples
Mariam’s class counts pulse at rest: 78 beats in a minute. After gentle stepping it is higher, because the muscles need more oxygen.
roots take in water→water rises in the stem→leaves let out vapour→droplets in the bag
Ahmed puts a plastic bag over a leafy branch in the sun. Droplets appear inside the bag. They came from the leaves, not from a leak.
Chain
Producer
Top animal
Nile
algae and water plants
crocodile
desert
plants and seeds
fennec fox or viper
A Nile food chain: algae, tilapia, perch, crocodile. A desert chain: seeds, jerboa, fennec fox.
Class activity
Chain challenge. Draw a food chain with four boxes for a place near you: a garden, a pond or a canal. Put arrows from the food to the eater. Then add one more animal that also eats the second box and show how it makes a web.
Practice
1
Which organs filter the blood to make urine?
The kidneys.
2
What do leaves take in and give out in photosynthesis?
They take in carbon dioxide and water and give out oxygen (and make sugar).
3
What is transpiration?
Water vapour leaving the leaves through tiny pores.
