Nutrition (2e) Flashcards
Photosynthesis word equation:
………………………………………sunlight………………………………
Carbon dioxide + water ———–> glucose + oxygen
……………………………………chlorophyll…………………………….
Where does photosynthesis happens?
Photosynthesis happens in the chloroplasts in the leaves of the plant, oxygen is released through the stomata
Photosynthesis balanced chemical symbol equation:
6CO2 + 6H2O —-> C6H12O6 + 6O2
Photosynthesis =…
Making food using light
Factors affecting rate of photosynthesis:
-Temperature
-Light intensity
-Carbon dioxide concentration
-Chlorophyll concentration
Temperature affects:
-How much kinetic energy particles have (speed at which carbon dioxide and water move though a plant)
Light intensity affects:
-The amount of energy that the plant has to carry out photosynthesis (more light faster rate of photosynthesis)
Carbon dioxide concentration affects:
-The faster the reaction can occur
Leaf adaptions
-Thin (to allow gases to diffuse easily)
-Can change direction (to face the sunlight)
-Large surface area (to absorb more light)
-Waxy layer on top of the leaf (to reduce water loss)
-Chloroplasts (contain chlorophyll that absorbs light energy from the sun)
-Veins (to transport water to the leaf and glucose away from the leaf)
-Many stomata ( to allow gas exchange)
Mineral ions…
For growth
magnesium ions…
essential for producing chlorophyll
nitrate ions…
make amino acids
A balanced diet should include…
Appropriate proportions of:
-Carbohydrate
-Protein
-Lipid
-Vitamins
-Minerals
-Water
-Dietary fibre
Carbohydrate
Source of energy (bread, cereals, pasta, rice, potatoes)
protein
Growth and repair (meat, fish, eggs, pulses, nuts)
Lipid
Insulation and repair (Butter, oil, nuts)
Dietary fibre
Helps food moving along the alimentary canal and helps peristalsis (whole grain cereals and fruit and vegetables)
Calcium
Strong bones and teeth (Milk, cheese, eggs)
Iron
Help carry oxygen (red meat, liver, eggs, some vegetables e.g. spinach)
Water
needed for chemical reactions to take place in cells (water, juice, milk, fruits and vegetables)
Vitamin A
chemical in the retina and also protects the surface of the eye (fish, liver, oils, butter, carrots)
Vitamin C
Sticks together cells (fresh fruits and vegetables)
Vitamin D
Help bones absorb calcium and phosphate (fish, liver oils and sunlight)
Amount of energy varies due to the following factors:
-Age
-Activity levels
-Pregnancy
Age
The energy needs of adults go down as they age. For example, people in their 50s need about 17% less energy in their diet than people in their 30s.
Activity levels
People who are active tend to need more energy than sedentary people. For example, an adult office worker might need 10,000 kJ per day, but a manual worker might need 15,000 kJ per day.
Pregnancy
In general, the greater a person’s mass, the more energy they need. Men tend to need more energy than women, and a woman’s energy needs increase when she is pregnant. This is mainly because she is carrying
extra mass.
Mouth
-Chemical digestion occurs when the enzyme amylase in the saliva breaks down starch into maltose.
-Mechanical digestion occurs as the teeth break down food.
Oesophagus
Chewed lump of food passes from the mouth into the stomach via a tube called oesophagus or gullet.
Stomach
Mechanical digestion occurs as the muscular stomach churn up the food. Hydrochloric acid present to kill bacteria and protecting us from poisoning
Duodenum
Bile and pancreatic juice are both alkali in order to neutralize the food covered in stomach acid
Ileum
Very large surface to be absorbed into the blood
Large intestine
Absorb water (colon) and indigestible fibre called faeces is stored in the rectum and expelled through the anus (egestion)
Pancreas
Produces all three types of digestive enzymes (amylase, protease and lipase)
Peristalsis
-Muscles in the walls of the oesophagus create a wave of contractions.
-Circular muscles contract to reduce the diameter of the lumen of the oesophagus or small intestine.
-Longitudinal muscles contract to reduce the length of that section the oesophagus or small intestine.
Role of enzymes
Biological catalysts to speed up chemical reaction
Carbohydrases
-Break down carbohydrates to simple sugars such as glucose
-Amylase breaks down starch into maltose
-Maltase then breaks down maltose into glucose
Proteases
-Group of enzymes that break down proteins into amino acids
-Pepsin breaks down proteins into smaller polypeptide chains
-Proteases made in the pancreas and small intestine break the peptides into amino acids
Lipases
-Lipases are enzymes that break down lipids (fats) to glycerol and fatty acids
-Lipase enzymes are produced in the pancreas and secreted into the small intestine
Bile
Produced by the liver and stored in the gall bladder
Role of Bile
two main roles:
-Neutralising the hydrochloric acid from the stomach
-Breaking apart large drops of fat into smaller ones
Adaptations of the Small Intestine
-The small intestine is adapted for absorption as it is very long and has a highly folded surface with millions of villi
-Peristalsis helps by mixing together food and enzymes and by keeping things moving along the alimentary canal
Villi of the small intestine specific adaptations:
-A large surface area (increases absorption)
-Short diffusion distance (one cell thick)
-Network of blood capillaries
