That chemical is a ______.
Blood vessels are part of the circulatory system.
The earth's atmosphere is one-fifth ______.
When conducting an experiment, make sure you follow the ______ carefully.
Platypuses are among the few egg-laying mammals.
We're studying the differences between solids, liquids, and gases.
A tick is a small biting ______.
All living things _______.
We made a simple ________ of sugar and water.
Wasps are important predators.
The deeper you swim, the greater the water ________.
Bacteria is a single celled ________.
The tree needs nutrients from the soil to survive.
Subatomic _________ are even smaller than atoms.
The human body is warm and moist, providing an ideal environment for bacteria to _________.
Platinum is chemically inert and so is useful in __________ apparatus.
About 4% of animal species are vertebrates.
We are studying the differences between aerobic and anaerobic ___________.
The ___________ in the desert was over 40 degrees.
The ___________ gave an accurate measure of the temperature of the room.