Biology - Humans as Organisms Flashcards
What are carbohydrates important for?
Provide fuel (energy) for the body
What are proteins important for?
Growth and repair
What is fibre important for?
Helps move food through the digestive system
What causes obesity? Use the concept of energy to describe your answer.
When someone takes in more energy from their diet than they use up.
What determines the amount of energy someone needs each day?
Their body mass and level of activity
What are the main two steps to breaking down food (what happens in the mouth and then what happens in the digestive system)?
Breaking down food mechanically by chewing
Breaking down food chemically with enzymes
How does bacteria in the stomach get killed?
There is hydrochloric acid in the stomach which is a low pH
Where in the digestive system is food absorbed?
Small intestines
Where in the digestive system is water absorbed?
Large intestines
What three types of enzymes does the pancreas make?
Protease to digest protein
Carbohydrase to digest carbohydrates
Lipase to digest lipids
What is the role of enzymes in the digestive system and why is it important to help us absorb food?
Break down large molecules into smaller soluble ones so that it can pass through the gut wall and go into the bloodstream
What are the finger-like projections found in the small intestines which help to absorb food? And how are these adapted to do so?
Villi:
Thin outer layer of cells
Good blood supply
Large surface area
What is the role of good bacteria in the gut?
They produce enzymes that help digest food.
They produce useful hormones and vitamins
They reduce the possibility of harmful bacteria growing in the intestines
Which two nutrients does the body get the most energy from?
Fats and carbohydrates
Where in the body are blood cells produced?
In the bone marrow
What are antagonistic muscles?
Muscles that work in pairs, one muscle contracts while the other relaxes and vice versa.
One muscles pulls the bone in one direction and the other pulls the bone in the opposite direction.
For example biceps and triceps.
Where in the lungs does gas exchange take place?
In the alveoli (air sacs)
Describe the gas exchange that happens in the lungs
Oxygen breathed in diffuses into the blood stream from the air sacs. Carbon dioxide (the waste product) diffuses out of the blood and into the air sacs to be breathed out.
What muscle in the bone is responsible for making us breathe?
The diaphragm
Describe how the diaphragm works.
When the diaphragm contracts it moves downwards, this increases the volume in the chest cavity and so decreases the pressure in the chest cavity and then air moves inside the lungs.
Why does exercising increase breathing rate?
Muscles need more energy, therefore the cells need more oxygen for respiration, so you breath faster to get more oxygen into your body and also to remove the extra carbon dioxide being produced by the muscles
What are symptoms of Asthma?
Difficulty breathing
Wheezing
A tight chest
How does smoking affect the lungs?
Tar covers the cilia which reduce it ability to move mucus up and out form the lungs. Smoke also contains carbon monoxide, nicotine and particulate which are bad for your lungs.
Describe a persons airways during an asthma attack
The airways get narrower
What are gametes?
Sex cells
Where does the sperm meet the egg?
Fallopian tube (or oviduct)
What two steps need to happen for a female to get pregnant?
Fertilisation and implantation
How many days does the menstrual cycle last?
28 days
What causes a women’s period?
If a fertilised egg does not implant in the uterus, then it will break down and will shed away out of the vagina
After fertilisation, when the egg has divided into 32 cells, what is it now called?
An embryo
How does a foetus in the mother get food and oxygen?
Through the placenta
What are recreational drugs?
Drugs used for enjoyment rather than for medical purposes
Give examples of legal and illegal drugs
Paracetamol, caffeine are legal
Cocaine and LSD are illegal
