Kidneys And Food

Question 1

What are proteins made of? What are they for?

Answer 1

• elements C, H, O, N and sometimes S
• made up of amino acids
• needed to maintain cell function and repair cells and tissues

Question 2

How do you test for protein? Where do you find it?

Answer 2

• biuret reagent. Light blue to purple

* seafood, meat, eggs

Question 3

What is fibre made of? why do we need it? Where is it found?

Answer 3

• elements C, H, and O
• 1000s of glucose molecules
• needed to help keep dig system healthy and prevent constipation. Can’t digest
• found in cereals, rice, beans, nuts

Question 4

What are minerals? Why do we need them? Where are they found?

Answer 4

• salts needed by body in small amounts, e.g. Calcium to keep bones healthy, iron for haemoglobin
• in milk and meat

Question 5

What are vitamins? Why do we need them? Where do we find them?

Answer 5

• organic substances needed in small amounts
A: good vision, maintenance and formation of skin, immune system(anti-oxidants). Dairy, eggs, fatty fish, mango, spinach
C: aids absorption of iron and copper, helps fight infection. Citrus fruit, blackcurrants
D: aids absorption of calcium. Found in sunlight on skin

Question 6

Why do we need water?

Answer 6

• carry substances around body and replaced lost water

Question 7

What are carbohydrates made of? Why do we need them?

Answer 7

• C, H, and O

* short term energy storage. Mono- use in resp, quick energy. Poly- broken down into glucose for resp

Question 8

How do you test for carbohydrates? Where do you find them?

Answer 8

• mono- benedict’s reagent. Blue ➯ brick red when heated
Sugar, cakes, etc.
• poly- iodine. Brown ➯ blue/black
Bananas , brown rice, potatoes

Question 9

What are lipids made of? Why do we need them? Where are they found?

Answer 9

• made of C, H, and O
• glycerol and 3 fatty acids
• long-term energy storage
• eggs, fish, milk

Question 10

How do you find out the energy in a sample of food?

Answer 10

• fill boiling tube w water
• weigh water
• measure temp at start
• wound food on needle and burn under water
• measure temp at end
Energy (cal) = (mass of water x temp rise) / mass of food

Question 11

What is peristalsis?

Answer 11

Series of wave like contractions to move food along to the digestive system. Mechanical action is needed

Question 12

How is absorption made efficient?

Answer 12

• large SA w many villi and microvilli
• short diffusion distance, villus wall thin and close to blood vessels
• high conc gradient. Rich blood supply has low conc of food molecules ∴ food diffuses quickly

Question 13

What are the types of digestion?

Answer 13

• mechanical, e.g. Teeth

* chemical, e.g. Enzymes

Question 14

What are enzymes?

Answer 14

Biological catalysts in metabolic reactions. Work by lower activation energy. Different enzymes catalyse only their particular reaction, as each amino acids folds a different way to form the active site where the substrate binds. The substrate shape is complementary to the active site.

Question 15

What are anabolic and catabolic reactions?

Answer 15

Catabolic- breaking down

Anabolic- building up

Question 16

How does temperature affect enzymes?

Answer 16

• below optimum temp:
Lower RoR. KE increases as temp increases ∴ more collisions and substrate base-combos ∴ RoR increases
• optimum temp: (roughly 37 °C) highest RoR
• above optimum temp:
Enzymes denature, active site changes shoe, RoR decreases rapidly

Question 17

How does pH affect enzymes?

Answer 17

• below/above optimum pH
➯ enzymes denature
➯ active site changes chape
➯ fewer substrate-base combos
∴ RoR decreases rapidly
• optimum pH
➯ highest rate of reaction

Question 18

What happens in the mouth?

Answer 18

Starch turns into maltose, ∵ of amylase from salivary gland

Question 19

What happens in the stomach?

Answer 19

• proteins digest in to amino acids by pepsin made in stomach lining
• stomach v acidic ∵ pepsin work best at low pHs

Question 20

What happens in the duodenum?

Answer 20

• starch breaks down into maltose via amylase made in salivary gland, and then into glucose via Maltase made in pancreas
• proteins digested into amino acids by trypsin, from pancreas
• lipids are digested into glycerol and fatty acids by lipase form pancreas, and helped by bile

Question 21

What does bile do?

Answer 21

• produced in liver and stored in gall bladder
• neutralises pH as food leaves stomach
• emulsifies lipids into droplets ∴ larger SA for lipase action

Question 22

What is an experiment to study the effect of temperature on enzymes?

Answer 22

• cut potatoes into small cubes
• get 5 test tubes and pt 3cm of hydrogen peroxide in each
• add 10 cubes to each test tube
• incube for 10 mins at different temps (e.g. 35, 30, 35, 40, 45)
• record height of oxygen bubble produced

Question 23

What is digestion?

Answer 23

Large insoluble food molecules broken down into smaller ones

Question 24

What is absorption?

Answer 24

Soluble molecules produced by digestion are taken from gut (mostly small intestine) and transported around body via circulatory system

Question 25

What is assimilation?

Answer 25

Cells of tissues absorbing the molecules for use

Question 26

What is egestion?

Answer 26

Removal of indigested waste products as faeces

Question 27

What is excretion?

Answer 27

Removal of things used in cells processes, via urine and sweat

Question 28

What are the medulla, pelvis, cortex, and nephron?

Answer 28

Medulla- lighter middle layer of kidney
Pelvis- central cavity which collects urine
Cortex- darker outer layer
Nephron- filtration unit where urine is prduced

Question 29

How do we remove waste from the body?

Answer 29

Skin- urea, water, salt, via sweat
Mouth- CO2, water, via exhalation
Kidneys- urea, water, salt, via urine

Question 30

What are the purposes of the kidneys?

Answer 30

Excretion- getting rid of urea and excess alt from blood

Osmoregulation- reabsorbing moe/less water into blood to maintain correct conc

Question 31

Why do we need to remove waste?

Answer 31

• urea toxic and produces ammonia
• excess water has osmotic effect and can burst cells
• excess salt is bad for osmotic effect and can effect metabolic processes

Question 32

What is in urine vs clean blood?

Answer 32

Urine: urea, some salts, some water

Clean blood: amino acids, cells, glucose, proteins, some water, some salts

Question 33

What happens in the nephron?

Answer 33

Ultrafiltration:
➯ blood arrives at glomerulus at high pressure, and small molecules squeeze through pores in wall into the bowman’ capsule
➯ blood cells/large molecules stay in blood ∵ too big to fit through
Selective reabsorption:
➯ useful molecules, e.g. Glucose, amino acids move back into blood via active transport
➯ some water moves into blood via osmosis
➯ urea stays in filtrate
➯ cells lining PCT have many mitochondria for resp for active trans
➯ have a folded membrane ∴ large SA
3. Water reabsorbed into blood via collecting duct. Urea + excess water becomes urine

Question 34

What happens when you are thirsty?

Answer 34

• lower water conc in blood
• hypothalamus stimulates pituitary gland to release ADH
• ADH makes collecting duct more permeable
∴ more water reabsorbed into blood and less urine produced
Negative feedback:
• thirst centre in hypothalamus stimulated
• ∴ you drink
• water conc in blood rises

Question 35

What happens when you are not thirsty?

Answer 35

• high water content in blood
• hypothalamus does not stimulate pituitary gland to release ADH
• makes collecting duct less permeable to water
• less water reabsorbed into blood, more urine produced

Question 36

What happened in dialysis?

Answer 36

• blood enters machine and flows between dialysis membranes
• dialysis fluid has salt, amino acids, glucose and water in normal quantities, but no water ∴ urea and excess salt/water are removed via diffusion/osmosis into the fluid
• fluid w urea discarded whilst cleaned blood goes back to body