Nutrition Flashcards
What is the word equation for photosynthesis?
Water + carbon dioxide (+ light energy) —> glucose + oxygen
What is the balanced symbol equation for photosynthesis?
6CO2 + 6H2O —> 6O2 + C6H12O6
What is a limiting factor?
- Factor in a reaction which is in shortest supply
- Lack of this factor is the reason why the rate of reaction no longer increases
What are the limiting factors of photosynthesis?
- Carbon dioxide
- Light intensity
- Temperature
- Increasing any of the above will increase the rate of photosynthesis until another factor
becomes limiting
Why is the rate of photosynthesis low in the morning?
- Temperature is the limiting factor
- Low temperatures inhibit enzyme activity
- Carbon dioxide levels are high
Why is the rate of photosynthesis high at midday?
- High temperature maximises enzyme activity
- Carbon dioxide is the limiting factor as it’s in the shortest supply
How is the leaf adapted for its role?
- Waxy cuticle
- Upper epidermis
- Palisade mesophyll
- Air spaces in spongy mesophyll
- Xylem
- Guard cells
- Stomata
- Thin and broad (large surface area)
The function of waxy cuticle
prevents evaporation of water and stops pathogen entry
The function of Upper epidermis
transparent to allow light to enter the leaf
The function of Palisade mesophyll
contains lots of chloroplasts for photosynthesis
The function of Air spaces in spongy mesophyll
to allow gases to diffuse
The function of Xylem
allows entry of water and mineral ions by transpiration stream
The function of Guard cells
control opening and closure of stomata
The function of stomata
allow carbon dioxide to enter, oxygen and water to leave
What does the plant use glucose for?
- Making cellulose cell walls
- Making proteins and DNA
- Making starch for storage
- Making sucrose for transport
Use and deficiency symptom of nitrate
Making amino acids and proteins; Stunted growth
Use and deficiency symptom of magnesium
Making chlorophyll; Yellow leaves
Protein: role, food rich in protein
Growth and repair of muscles; Meat, fish, eggs, cheese
Carbohydrates: role, food rich in carbohydrates
Source of energy Glucose - fruits and vegetables Lactose - milk Sucrose - table sugar Starch (insoluble) - potato, rice, wheat Glycogen - meat Cellulose - plant cell walls
Lipids: role, food rich in lipids
Insulation and longterm energy store
Butter, cheese
Role of water?
Supports chemical reactions inside cells
Fibre: role, food rich in fibre
Prevents constipation
Vegetables
Calcium: role, food rich in calcium
Strong teeth and bones
Milk, cheese
Iron: role, food rich in iron
Healthy blood
Red meat
Vitamin A: role, food rich in vitamin a
Good vision
Fish liver oils, butter, carrots
Vitamin C: role, food rich in vitamin c
Sticks together cells lining the mouth
Lemons, oranges
Vitamin D: role, food rich in vitamin d
Strong bones
Fish liver oils, made by skin in sunlight
How do energy requirements vary with activity levels?
Age - older people need less food than young people as activity levels are lower
Pregnant women need more food, iron, and calcium to support growing baby
Why is food needed?
- For growth and repair of tissues
- Fight disease
- Supply fuel needed to release energy
What is digestion?
- The break down of large, insoluble molecules into small, soluble ones
- For absorption through the wall of the small intestine
What is mechanical digestion?
- Physical breakdown of food
- E.g. Teeth chew food, muscles in stomach churn food
What is chemical digestion?
Enzymes act as biological catalysts and break down large, insoluble molecules into small,
soluble ones
Where is bile made, stored, and released into?
Liver, gall bladder, small intestine
What is the role of bile?
Emulsifies - breaks down large lipid droplets into small ones to increase the surface area
Neutralises hydrochloric acid
What is the role of hydrochloric acid (HCl)?
Kills pathogens
What is the role of the stomach?
- Contains HCl to kill pathogens (chemical digestion)
- Muscular walls churn food (mechanical digestion)
How does digestion start in the mouth?
- Mechanical breakdown of food by teeth
- Amylase released
- digests starch into glucose
What is peristalsis?
- Contraction and relaxation of circular and longitudinal muscles which push food along the gut
What is the role of maltase?
To digest maltose into glucose
What is role of amylase?
To digest starch into maltose
What is the role of lipase?
To digest lipids into fatty acids and glycerol
What is the role of protease?
To digest proteins into amino acids
Where is amylase made?
Salivary glands, small intestine, pancreas
Where is lipase made?
Pancreas, small intestine
Where is protease made?
Pancreas, small intestine, stomach
How is the small intestine adapted for its function?
- Large surface area provided by villi and microvilli
- Lots of capillaries
- Thin wall - short diffusion distance
- Lacteals - absorption of fats
What is ingestion?
When food enters the mouth
What is excretion?
The removal of waste products of metabolism
What is absorption?
The movement of soluble food through the wall of the small intestine into the blood stream
