An adult has a body mass of 54 kg and a brain mass of 1.35 kg…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
An adult has a body mass of kg and a brain mass of kg. The body uses kcal in a day, and the brain uses about of that energy at rest, a standard value that NCERT does not give.
- What per cent of the body mass is the brain?
- How many kilocalories does the brain use in a day?
Need a reminder? The key ideaShow
The brain is protected by the skull and the cranial meninges: the dura mater (outer), the arachnoid (thin, middle) and the pia mater (inner, on the brain tissue). The forebrain has the cerebrum (two hemispheres joined by the corpus callosum), the thalamus and the hypothalamus. The cortex is the grey matter, with motor, sensory and association areas. The limbic system has the amygdala and the hippocampus.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Body: kg. Brain: kg. Energy: kcal a day, of it for the brain.
Plan. Use a per cent twice.
Step 1. Share of the mass. .
Step 2. Energy. kcal.
Answer: ; kcal.
Check. The brain is a small part of the body, but it uses a large share of the energy: against of the mass.
Watch out. The per cents are of different things. One is a share of the mass and the other is a share of the energy.
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