Biology: Age 14

11 illustrated Biology lessons for Age 14.

Chromosomes, DNA and genes Your cells carry instructions in DNA, which is packed into chromosomes inside the nucleus. A gene is one short…
Chromosomes and genes Inside the nucleus of nearly every human cell are 46 chromosomes, which form 23 matched pairs. A gene is a sho…
How a snail builds its shell A snail's mantle, the soft tissue at the shell opening, makes a thin flexible layer of organic material. It th…
Gas Exchange in the Alveoli Deep in your lungs, millions of tiny air sacs called alveoli are wrapped in thin blood vessels. Oxygen moves f…
Air moving in and out Your chest changes size because of two sets of muscles: the dome-shaped diaphragm under the lungs and the musc…
Blocking the Pain Signal Painkillers can stop an enzyme from making prostaglandins. With less prostaglandin, nerve endings are less sen…
Allergy Response The immune system mistakes a harmless substance, such as pollen, for a dangerous invader. Antibodies on a whit…
Smoke reaches the air sacs Inhaled smoke travels down the airways to tiny air sacs in the lungs. There, carbon monoxide slips into the bl…
DNA in Living Things Most living things carry DNA inside their cells. The exact DNA pattern is different for each person.…
Aircraft Fluid Removal Before an aircraft is cut apart, fuel and hydraulic fluid are drained through hoses into sealed drums. Batteri…
One gene copy from each parent Every living thing gets one copy of each gene from each parent, so it has two versions of every trait. When th…