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biology > B2 - Principles Of Organisation And Digestion > Flashcards

B2 - Principles Of Organisation And Digestion Flashcards

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AP® Biology flashcards
1
Q

What is a tissue?

A

A tissue is an aggregation of cells with a similar structure and function

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2
Q

What is an organ?

A

An organ is an aggregation of tissues working together to perform a particular function

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3
Q

What is an organ system?

A

An aggregation of organs, which work together to form functioning organisms

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4
Q

What is a cell?

A

The basic building block of all living organisms

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5
Q

Why does food need to be digested?

A

To break down large, insoluble biological molecules into small, soluble ones by enzymes so that they can be absorbed in the bloodstream

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6
Q

What are the function of digestive enzymes?

A

Digestive enzymes convert food into small, soluble molecules that can be absorbed into the bloodstream

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7
Q

What digestive enzyme breaks down carbohydrates?

A

Carbohydrases.

Amylase is a carbohydrase which breaks down starch into maltose

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8
Q

What digestive enzyme breaks down protein?

A

Proteases

Example: Pepsin

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9
Q

What digestive enzyme breaks down lipids (fats)?

A

Lipases

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10
Q

What are the products of digestion used for?

A

The products of digestion are used to build new carbohydrates, lipids and proteins.

Some glucose is utilised in cellular respiration

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11
Q

Where is bile made, stored and released?

A

Bile is made in the liver, stored in the gall bladder and released into the small intestine

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12
Q

What is the function of bile?

A

Bile catalyses the digestion of lipids by converting large lipid droplets into smaller ones.

It is not an enzyme

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13
Q

Explain how bile increases the rate of lipid breakdown by lipase

A

Bile emulsifies lipids to form small droplets. This increases the S.A for enzymes to act on. Bile also is alkaline to neutralise HCI from the stomach (enzymes in the small intestine have a more alkaline pH than those in the stomach) so that the enzymes do not denature. These both increase the rate of lipid breakdown by lipase to form fatty acids and glycerol

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14
Q

(i) What is the qualitative reagent test for
carbohydrates/sugars? What is its positive result?

(ii) What are the different types of carbohydrate that can be tested for?

A

(i) Benedict’s solution.

Positive result: Blue -> Green/yellow/brick-red precipitate, depending on concentration

(ii) Glucose using Benedict’s and starch using iodine

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15
Q

How is the small intestine adapted for absorption?

A

Long in length at around 5m. This increases the surface area for absorption of the products of digestion

Interior is covered with villi. Microvilli on the surface increase the surface area further

Rich blood supply in vili. This allows for the bloodstream to remove the products of digestion, increasing the concentration gradient

Villi have a thin membrane. This ensures a short diffusion pathway

High yield of mitochondria in intestine lining cells to release energy for any molecules that cannot be absorbed into the bloodstream by diffusion and require active transport

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16
Q

What do carbohydrases break down carbohydrates into?

A

Simple sugars

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17
Q

What do proteases break down proteins into?

A

Individual amino acids, which are then absorbed into the bloodstream

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18
Q

What do lipases break down lipids into?

A

Glycerol and fatty acids. This makes the pH more acidic

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19
Q

What is the qualitative reagent test for starch? What is its positive result?

A

Iodine solution

Positive result: Orange -> blue/black

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20
Q

Where is amylase, a carbohydrase that breaks down starch into sugar (maltose), produced? [SgPSm]

Where does it work?

A

Produced in:

Salivary glands
Pancreas
Small intestine

Works in:

Mouth
Small intestine

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21
Q

Where is protease produced? [SPSm]

Where does it work?

A

Produced in:

Stomach
Pancreas
Small intestine

Works in:

Stomach
Small Intestine

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22
Q

Where is lipase produced? [SP]

Where does it work?

A

Produced in:

Pancreas and small intestine

Works in:

Small intestine

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23
Q

What is the function of the stomach?

A

Produces HCI to kill bacteria and to provide the optimum pH for the protease enzyme to function

24
Q

What is the function of the small intestine?

A

The site where soluble molecules are absorbed into the blood by cellular transport

25
Q

What is the function of the liver?

A

Releases bile into the small intestine to emulsify fat and neutralise stomach acid

26
Q

What is the function of the large intestine?

A

Absorbs water from undigested food to produce faeces. This passes out of the body through the rectum and anus

27
Q

Without bile to neutralise acid in the stomach, the enzymes would become ______

A

Denatured

28
Q

Amino acids are used to build proteins such as _______ and ________

A

Enzymes and antibodies

29
Q

Fatty acids and glycerol can be used to build new ____________ and ____________

A

Cell membranes and hormones

30
Q

Some glucose released from carbohydrate breakdown is used in ______ to release energy to fuel all the activities of the cell

A

Respiration

31
Q

What is the function of muscular, glandular and epithelial tissue?

A

Muscular tissue - moves the stomach walls to churn food
Glandular tissue - makes digestive juices
Epithelial tissues - covers the outside and inside of the stomach

32
Q

What is the digestive system?

A

Several organs working together to digest and absorb food

33
Q

What are enzymes?

A

Enzymes are biological catalysts that are 3D, large (tertiary) proteins made up of a chain of amino acids

34
Q

Enzymes catalyse specific reactions in living organisms due to the ____ of their ________

A

Shape
Active site

35
Q

What is the lock and key theory model of enzyme action?

A

The substrate is perfectly complementary to the active site. This forms an enzyme-substrate complex and products

36
Q

What factors affect enzyme action?

A

Temperature
pH

37
Q

What is a catalyst?

A

A substance which increases the rate of reaction without getting used up

38
Q

Describe the process of human digestion

A

Mouth -> mechanically churns food. Salivary glands produce salivary amalyse to digest insoluble food molecules. This passes through the oesophagus into the stomach

Stomach -> pummels food with muscular walls, produces pepsin and HCI. Churning action turns food into fluid, increasing S.A for enzymes

Small intestine -> Bile released into the small intestine, which increases the rate of fat breakdown. All digestive enzymes break down large, insoluble molecules into small, soluble ones to be absorbed in the bloodstream through diffusion or active transport

Wastage —> Fluid goes to large intestine. Excess water absorbed into the bloodstream. Faeces stores in rectum before leaving through anus

39
Q

Describe a method to prepare food samples

A

Break food using pestle and mortar
Add distilled water
Stir and filter to remove insoluble bits of food

40
Q

Describe a method to test for sugars

A

Transfer 5cm³ of food sample to a test tube
Prepare a water bath at 75 degrees Celsius
Add 10 drops of Benedict’s solution
Place each test tube in water bath for five minutes

If green —> small concentration of sugar
If yellow —> moderate concentration
If Red —> highest concentration

41
Q

Describe a method to test for starch

A

Transfer 5cm³ of food sample to a test tube
Add 3 drops of iodine solution
Positive result is blue-black

42
Q

Describe a method to test for proteins

A

Transfer 2cm³ of food sample to a test tube
Add 2cm³ of Biuret solution
Positive result is purple from blue

43
Q

Describe a method to test lipids (write both methods)

A

Transfer 5cm³ of food sample to a test tube
Use a pipette to add three drops of Sudan III
If a red layer forms, lipids are present

44
Q

Suggest how damage to the mucus lining of the stomach might result in a stomach ulcer forming

A

Bacteria not killed by HCI so damage the mucus lining

So acid damage tissues

45
Q

Explain how temperate affects how enzymes function

A
46
Q

Explain how enzymes break down substrates

A

Substrate fits into active site of the enzyme
Shape of active site is specific to the enzyme and forms an enzyme-substrate complex
Bonds within substrate are broken

Enzyme is not used up !

47
Q

Give one industrial use of carbohydrase, isomerase and protease

A

Carbohydrase -> converts starch info sugars

Isomerase -> converts glucose syrup to fructose syrup

Protease -> pre-digests proteins in baby food

48
Q

Describe a method to investigate the effect of pH on the rate of reaction of amylase enzyme.

A
  1. Set up a water bath or electric heater at 25-35 degrees
  2. Place 3 drops of iodine solution into each well of a spotting tile
  3. Using a syringe, place a 2cm³ solution of amylase, starch and pH 5 buffer solution into three different boiling tubes
  4. Place all three boiling tubes into the water bath and wait 5 minutes for them to equilibrate
  5. Mix the boiling tubes and start a timer
  6. Every 30 seconds, place a drop from the boiling tube into the well
  7. Continue step 6 until the well remains orange. At this point, the starch has been fully digested. Record this time
  8. Repeat the investigation using different pH buffer solutions such as 7 and 12
  9. Repeat for each pH three times, remove anomalies and calculate a mean rate of reaction
  10. Calculate the rate of reaction using: Reaction = 1000/time
49
Q

What is the IV, DV and CV for investigating the effect of pH on the rate of reaction of amylase enzyme?

How can the investigation be improved?

A

IV- pH
DV-
CV- Temperature

50
Q

Suggest an explanation as to why the rate of reaction is slow at certain pH levels

A

High and low pH values may cause bonds holding enzymes’ structure together to break

51
Q

Explain how the cells of the pancreas are specialised to produce enzymes

A
  • Pancreatic cells have many ribosomes. This is the site of protein synthesis
  • Many mitochondria to release energy for protein synthesis
52
Q

Read questions in exams TWICE for every subject

A
53
Q

Describe the structure of the heart

A

Muscular walls to provide a strong heartbeat

The muscular wall of the left ventricle is thicker, because blood needs to be pumped all around the body

Four chambers that separate oxygenated blood from the deoxygenated blood

Valves to make sure the backflow of blood does not occur

Coronary arteries cover the heart to provide its own oxygenated blood supply

54
Q

Where is carbohydrase produced?

A
55
Q

A person has a tumour blocking the tube leading from the gall bladder to the small intestine

ExplaIn why this person would have difficulty digesting fat (5)

A
  • No bile reaches the small intestine
  • So less emulsification fat
  • So smaller surface area for lipase to break down fat
  • pH of small intestine is not neutralised/alkaline
  • So lipase is not at its optimum pH to break down fat

biology (9 decks)

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