Digestion Flashcards
Why do we need food (3)
- To supply us with fuel for energy
- To provide materials for growth and repair of tissues
- To help fight disease and keep our bodies healthy
What can cause rickets (2)
- Lack of vitamin d
- Lack of calcium
What is vitamin c used for and what can a deficiency in this cause
To make connective tissue
Scurvy
What is a source of vitamin c
Fresh fruit and veg
What is a source of vitamin a
Butter
What is vitamin a used for
Making a chemical in the retina, will go blind if not made
How to test how much energy is in a sample of food
Light the food on fire, then measure the temperature change of a test tube of water that is placed above the burning food.
Then find the mass by weighing, then use E = MCdeltaT to find the energy (where c = 4.2 and m = mass of water)
Then do E/mass of food
What is peristalsis
The circular muscles and the longitudinal muscles in the gut work together, one contracts and one relaxes, to push the food through the gut. - circular contract = narrower
Describe what happens to an eaten food (8)
- Chewed up into chunks and combined with saliva
- Passes down the oesophagus
- Goes into the stomach
- Enters the duodenum
- Enters the ileum
- Enters the colon
- Rectum
- Sent to anus as faeces
Where is amylase produced (2) and why
- Salivary glands
- Pancreas
This is because the amylase produced in the salivary glands will have its enzymes denatured by the stomach acid so can no longer function
What does lipase do
Breaks down lipids
What dies pepsin do
Breaks down proteins into peptides
What does peptidase do
Breaks peptides down into amino acids
What does amylase do
Breaks starch into maltose
What does maltase do
Breaks maltose into glucose
How does the stomach not digest itself due to the acid
There is a mucus layer
What is bile
A digestive fluid (NOT AN ENZYME) that is made in the liver and stored in the gall bladder. It passes down the bile duct to the food. The bile turns any large lipid globules into tiny droplets, so the surface area is bigger, so the lipase can break the lipid down quicker.
How is the illeum adapted to digest food (6 + one point that isn’t on markscheme but is relevant)
- Large surface area - folds in lining
- Villi and microvilli
- Good blood supply
- One layer of cells between food and blood - easy absorption
- Steep concentration gradient for diffusion of food
- Permeability of cells between blood and food
(6. Hepatic portal vein)
What does the large intestine do
It mainly only contains waste e.g. starch because all useful, digestible molecules were digested in the small intestine. Therefore, the codon abosrbs the remaining water, which leaves faeces behind, which is stored in the rectum, which is expelled from the anus
Go look at the carbon cycle and fill out a gap fill to test Knowledge - base rating off that
Go look at the nitrogen cycle and fill out a gap fill to test Knowledge - base rating off that
What happens to nitrogen in the form of ammonia
Nitrification, into nitrites (NO2-) then turned into nitrAtes by nitrifying bacteira (NO3-) then either assimilated into plants or is turned into N2 by denitrifying bacteira
What are the 2 things that can split a nitrogen bond
- Lightning
- Nitrogen fixing bacteira
Where are nitrogen fixing bacteira found
Root nodules of legumes
What happens to dead plant and animal matter
It is decomposed by decomposers like fungi and bacteira. The nitrogen is then turned into ammonia form by bacteira, in the process of ammonification
Why is nitrogen needed in the body
To make amino acids
