Page 71 - Science Class 07

risen. But there is no change in the tempera- ac vity shows that germina ng seeds produce
ture in which boiled seeds were kept. This heat during respira on.

Why do human beings yawn?
You might have no ced that when we remain in relaxed posi on for a long period of me, then
we start yawning. Actually, when we remain inac ve for a longer period of me our breathing
slows down and becomes more shallow. Therefore, our lungs do not get sufficient amount of
oxygen. To fulfill the requirement of oxygen we yawn. When we yawn we take in extra amount
of oxygen.

1. How do plants take in air?
2. How respira on is the reverse of photosynthesis?

3. Why people are not advised to sleep under a tree during the night?

4. What are len cels?
5. How do the roots of a plant respire?

Breathing : The mechanism of taking in and out air

Respiration : The process by which energy is released from the eaten food
Aerobic respiration : Process of respiration which requires air, i.e., oxygen
Anaerobic respiration : Process of respiration which does not require air

Fermentation : The process of anaerobic respiration in which yeast is used to break
down food item into other forms
Nasal cavity : It is a cavity present within the nasal passage and is separated from
oral cavity by a bony palate

Bronchi : The lower part of trachea divided into two smaller tubes
Alveoli : Tiny sac like structures attached to bronchioles
Inhalation : The process of taking air inside the body

Exhalation : The process of releasing air outside the body
Oxyhaemoglobin : Combination of oxygen and haemoglobin

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