Nutrition Flashcards
Photosynthesis equation
Carbon dioxide and water (light energy and chlorophyll) produces glucose and oxygen
Structure of leaf: cuticle
Reduces water loss by evaporation and acts as a barrier to the entry of bacteria and fungi
Structure of leaf: Upper epidermis
Has no chloroplast so maximum light can enter into main cells
Structure of leaf: Lower epidermis
Has many holes called stomata which allows the exchange of oxygen and carbon dioxide
Structure of leaf: Guard cells
Change their shape to open and close stomata
Structure of leaf: Palisade cells
Are long narrow cells containing many chloroplat hence maximum photosynthesis happens in these cells
Structure of leaf: Spongy cells
Are loosely packed round cells containing few chloroplast which carry out photosynthesis
Structure of leaf: air spaces
Found in between spongy cells allow diffusion of gases in and out of mesophyll cells
Structure of leaf: xylem
Transports water and minerals ions to the leaf cell from the roots
Structure of leaf: Phloem
Transports products of photosynthesis such as sugar from the leaf cells to different parts of the plant
Adaptation of leaf: (6)
Leaf is broad and flat shape offers a large surface area for the absorption of light.
No chloroplast in the upper epidermis allowing maximum light to pass through to the palisade cells.
More chloroplast are present on the palisade cells than spongy cells as they are the main photosynthesis cells and spongy cells form the main gas exchange surface of the leaf.
Large number of stomata present on the lower epidermis for the exchange of carbon dioxide and oxygen with the air outside.
Most leaves are thin so that carbon dioxide has to travel only to short distance to reach the mesophyll cells.
Branching network of veins provides a good water supply to the photosynthesizing cells.
Factor affecting the rate of photosynthesis
The process of photosynthesis depdns upon:
Light intensity
Carbon dioxide concentration
Temperature (suitable for enzyme)
Limiting factor
The factor in the shortest supply would determine the rate of reaction. So the factor in the shortest supply will limit the rate of reaction
Factors affect the rate of photosynthesis: light intensity
As the amount of light increases so does the rate. The limiting factor is light. increasing the intensity of light has no affect on the rate. The limiting factor now is carbon dioxide or temperature.
Factors affect the rate of photosynthesis: carbon dioxide
As the amount of carbon dioxide goes up so does the rate. The limiting factor is carbon dioxide. increasing the concentration has no affect on the rate. The limiting factor now is light or temperature.
Factors affect the rate of photosynthesis: temperature
As the temperature increases so does the rate. The limiting factor is temperature. Heat energy increases the energy of the reactants more collisions with more force thus increase the rate of reaction. Enzyme denatures.
Importance of mineral ions: nitrate
Are used to make amino acids and therefore proteins such as enzymes
Deficiency symptoms: nitrate
Limited growth and leaves turn yellow
Importance of magnesium ions: magnesium
It is part of chlorophyll
So is used to make chlorophyll
Deficiency symptoms: magnesium
Leaves turn yellow
Balanced diet
Consists of all the food groups in the correct proportions
The necessary key food groups are : (8)
Carbohydrates
Proteins
Lipids (fats)
Dietary
Fiber
Vitamins
Minerals
Water
Food type: carbohydrates
Function: source of energy
Sources: bread, cereal, pasta, rice, potatoes
Food type: protein
Function: growth and repair
Sources: meat, fish, eggs, pulses, nuts
Food type: lipid
Function: insulation and energy storage
Sources: butter, oil, nuts
Food type: dietary fibre
Function: provides bulk (roughage) for the intestine to push food through it
Sources: fruits and vegetables
Food type: vitamins
Function: needed in small quantities to maintain
Sources: fruit and vegetables
Food type: Minerals
Function: needed in small quantities to maintain
Sources: fruit and vegetables, meats, dairy products
Food type: water
Function: needed for chemical reactions to take place in cells
Sources: water, juice, milk, fruit and vegetables
Vitamin/mineral: calcium
Function: needed for strong teeth and bones and involved in the the clotting of blood
Sources: milk, cheese, eggs
Vitamin/mineral: vitamin D
Function: helps the body to absorb calcium and so required for strong bones and teeth
Sources: oil fish, liver, dairy products, also made naturally by the body in sunlight
Vitamin/mineral: vitamin C
Function: forms an essential part of collagen proteins which make up skin, hair, gum and bones
Sources:citrus fruits, strawberries, green vegetables
Vitamin/mineral: vitamin A
Function: needed to make the pigment in the retina for vision
Sources: meat, liver, leafy green vegetables, eggs
Vitamin/mineral: Iron
Function: needed to make haemoglobin the red pigment in the red blood cells that transports oxygen
Sources: red meat, liver, leafy green vegetables
Deficiency in calcium
Can lead to osteoporosis
Rickets
Deficiency in vitamin c
Causes scurvy
Deficiency in vitamin D
Rickets
Deficiency in Vitamin A
Night blindness
Deficiency in fibre
Constipation
Deficiency in Iron
Anaemia
Dietary needs: age
The amount of energy needed increases toward as adulthood as this energy is needed for growth. Children need a higher proportion of protein in their diet than adults as this is required for growth
Dietary needs: activity levels
The more active the more energy required for movement as muscles are contracting more and respiring faster
Dietary needs: pregnancy
Energy requirements increases as energy is needed to support the growth of the developing foetus as well as the larger mass that the mother ends to carry around. Extra calcium and iron are also needed in the diet to help build the bones, teeth and blood of the foetus
Phases of digestion
Ingestion
Digestion
Absorption
Assimilation
Egestion
Ingestion
The act of taking the food into your mouth
Digestion
The process of breaking down of food (chemical and mechanical)
Absorption
The process of taking the digested product into the blood stream
Assimilation
The various ways the body uses digested products
Egestion
The removal of undigested food out of the body
Physical digestion
The shape of the molecule must be physically changed so that it can fit through the diameter of the digestive system
Chemical digestion
This allows useful chemicals to be released and dissolve in the blood.
Teeth
Breaks down the food mechanically by the chewing action of teeth
Tongue
Roll the food into a bolus and helps in swallowing
Salivary glands
Produces saliva
Saliva contains
Water - to moisten the food
Mucin - sticks to food to make a bolus
Salivary amylase - chemical break down of starch to maltose
Digestion in mouth: physical digestion
The food is physically broken down by the chewing action of teeth
Digestion in mouth: chemical digestion
Starch to amylase to maltose
Digestion in oesophagus
After swallowing food moves though the oesophagus by a process called peristalsis.
Peristalsis leads to physical digestion of food. No chemical digestion takes place in oesophagus
Movement along the tubes of gut
Peristalsis is a wave-like contract and relaxation of circular and longitudinal muscles.
Behind the bolus circular muscles contract and longitudinal muscles relax
Ahead the bolus the circular muscles relax and longitudinal muscles contract
Digestion in stomach
The walls of the stomach secrete a liquid called gastric juice which contains:
Protease: an enzyme that breaks down proteins in stomach
Hydrochloric acid: provides a pH range of 1-3 in stomach as it is the optimum pH for enzyme pepsin. Low pH also kills any microorganisms that enters through food
Mucous: is a secretion which protects the stomach from being eroded or dissolved by the HCL
Digestion in stomach: physical digestion
The food is physically broken down by a process called churning action of stomach
Digestion in stomach: chemical digestion
The enzyme protease chemically breaks down proteins.
Protein to pepsin to polypeptides
Small intestine
Duodenum
Ileum
Duodenum
Is the first u-shaped part of the small intestine and almost all the digestion takes place here due to two secretions
1. Bile
2. Pancreatic juice
Pancreatic juice produced by
Pancreas
Bile secreted by
Liver
Bile is produced by
Liver
Bile is stored in
Gall bladder
Bile
Is released through the bile duct into the duodenum
Bile contains:
Bile salts - are involved in the physical digestion of fats. It emulsifies fats to help lipid digestion
Sodium hydrogen carbonate - neutralizes the acidic chyme and maintains an alkaline medium so that enzymes produced by pancreas can work well
Pancreatic juice
Pancreatic juice contains enzymes necessary for the digestion of starch (pancreatic amylase), protein (trypsin) and fat (lipase)
Starch to amylase to maltose
Polypeptides to trypsin to peptide
Fats to lipase to fatty acids and glycerol
Illeum
Finalizes the process of digestion & absorb the digested food
Illeum: digestion
Its walls secrete a liquid containing enzymes called intestinal juice which finalized digestion.
Maltose to maltase to glucose
Peptide to erepsin to amino acids
Fast to lipase to fatty acids and glycerol
Ileum: absorption
To make absorption more efficient ileum has a large surface area
Adaptation in ileum
It is about 6m long and the inner surface is highly folded to increase the surface area.
The surface area is further increased by finger like projections called villi
Adaptation in villi
Villi are able to move and its epithelial cells bear microscopic microvilli which further increases the surface area for absorption.
Villi are supplied with blood capillaries which absorb glucose and amino acids.
The wall of the villi is one cell in thickness to that digested food materials have to diffuse to only a short distance to reach the blood.
Lacteal absorb fatty acids and glycerol
Absorption in large intestine
The colon absorbs water, salts and vitamins. For more effective absorption its walls are folded to increase its surface area
Rectum
Is a muscular storage chamber where the undigested food (faeces) is held and molded before being pushed out through the anus during egestion
Anus
The anus is the exit through to the alimentary canal. It’s closed by a ring of muscle (anal sphincter) which is relaxed during egestion
Enzymes made in: amylase
Salivary glands
Small intestine
Pancreas
Enzymes made in: Protease
Stomach
Small intestine
Pancreas
Enzymes made in: Lipase
Small intestine
Pancreas
Amylase and maltase
Breaks down starch into glucose
Substrate: starch
Product: glucose
Protease
Breaks down Proteins into amino acids
Substrate: proteins
Product: amino acids
Lipase
Breaks down Lipids (fats) into fatty acids and glycerol
Starch
It is formed by plant. Presence of starch in a plant can be used as an evidence of photosynthesis
Destarching the plant
Plant needs to be kept in a dark place for 48 hours.
During this period it will not be able to photosynthesis and they will use up all, its starch for respiration.
Investigating oxygen is released during photosynthesis
Take an aquatic plant such as pond weed and place it in a water bath under an inverted funnel
Fill a boiling tube with water and place it over the end of the funnel
As oxygen is produced the bubbles of gas will collect in the boiling tube & displace the water
Remove the boiling tube and insert a glowing splint
Splint relights
Investigating presence of starch
Boil the leaf in a water bath. (Kill cells and break down the cell wall)
Bio the ethanol leaf in a ethanol for 5-10 mins. (To remove chlorophyll from the leaf)
Wash the leaf with cold water. (To decolorise the leaf)
Place the leaf on a white tile (iodine will change colour in the presence of starch)
Add drops of iodine (areas that contain starch will turn blue-black)
Investigating importance of light in photosynthesis
Destarch the plant by placing the plant in a dark cupboard for 48hrs.
Partially cover a leaf of the plant with aluminium foil and place it in sunlight for 24hrs.
Remove the covered leaf and carry out starch test.
Boil the leaf in a water bath.
Boil the leaf in ethanol for 5-10mins
Wash the leaf in cold water
Place the leaf on a white tile
Add few drops of iodine solution
Areas that does contain starch will remain brown
Areas that contain starch will turn blue-black.
Investigating importance of carbon dioxide in photosynthesis
Destarch the plant by placing it in a dark cupboard for 48 hours.
Enclose one leaf with a conical flask containing KOH and another without KOH. Leave the plant in sunlight for 24 hrs.
KOH (removes carbon dioxide from surrounding air).
Remove the two leaves and carry out starch test.
Boil the leaf in a water bath.
Boil the leaf in ethanol for 5-10mins
Wash the leaf in cold water
Place the leaf on a white tile
Add few drops of iodine
Miss Shabeena
Rate of photosynthesis
Is how many molecules of products are formed in a given period of time
Role of chloroplast
Is to absorb light energy during photosynthesis
