Nutrition Flashcards
Define the term enzyme
A protein; [1 mark]
A biological catalyst; [1 mark]
That helps to increase/speed up the rate of chemical reactions (in living organisms); [1 mark]
Ignore ‘catalyst’ on its own
How does bile help digestion?
It neutralises stomach acid / provides the optimum pH for enzymes/named enzymes (of the small intestine); [1 mark]
It emulsifies fat / breaks large fat droplets into smaller droplets / increases the surface area of fat droplets; [1 mark]
Human breast milk may contain insufficient vitamin D for a growing child.
Give two ways that additional vitamin D could be provided for the child.
(Exposure to) sun(light); [1 mark]
A named source of vitamin D, e.g. cod-liver oil/oily fish (such as salmon, sardines, herring and mackerel) / red meat /liver / eggs / fortified foods (such as most fat spreads and some breakfast cereals); [1 mark]
Add (vitamin D) drops (to food/drink) / use a (vitamin D) supplement; [1 mark]
Describe how a sample of cow’s milk could be tested for protein.
Add biuret (reagent/solution to the sample); [1 mark]
If protein is present (the sample) turns purple/lilac/violet; [1 mark]
Explain how food passes down the oesophagus.
Peristalsis; [1 mark]
(Waves of) muscular contractions; [1 mark]
The gut of a rabbit has a large caecum and appendix. These contain bacteria that are able to produce the enzyme cellulase.
Explain how these bacteria help the rabbits with their diet of plant material. [3]
(Plants contain) cellulose; [1 mark]
(Which is) digested/broken down by cellulase/enzyme…; [1 mark]
… into glucose; [1 mark]
Energy is released (from the glucose) / (glucose is a reactant for) respiration; [1 mark]
In humans, the appendix also acts as a store of useful bacteria. Scientists have discovered that patients who have had their appendix removed are more likely to develop infections of the colon.
Explain how having no appendix may increase the likelihood of bacterial infections of the colon. [2]
Removes useful bacteria / fewer/no useful bacteria; [1 mark]
Reduces competition (between pathogenic and useful bacteria); [1 mark]
Pathogenic bacteria increase/survive/multiply / there are more harmful bacteria; [1 mark]
Ignore mention of the appendix containing useful bacteria as this is mentioned in the question stem.
During digestion partially digested food moves from the stomach to the small intestine where several additional substances are secreted and digestion of carbohydrates continues.
These secretions include the following:
• A substance known as bile
• Pancreatic fluid containing pancreatic amylase, protease and lipase..
Explain why the rate of digestion by enzymes in the small intestine is not reduced by stomach acid.
[2]
Stomach acid is neutralised by the (alkaline) bile / bile is alkaline so neutralises/counteracts stomach acid; [1 mark]
Pancreatic amylase is released into the duodenum/small intestine (and not the stomach) which has a neutral pH; [1 mark]
