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gcse biology > b3 - organisation and the digestive system > Flashcards

b3 - organisation and the digestive system Flashcards

1
Q

what do cells do as a multicellular organism develops?

A

they differentiate

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2
Q

define tissues

A

group of cells with similar structure and function

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3
Q

give three examples of tissues

A

muscular tissue - contracts for movement
glandular tissues - produces substances like enzymes or hormones
epithelial tissue - covers some parts of body

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4
Q

what tissues is the stomach made up of?

A

muscular tissue - churn contents
glandular tissue - digestive juices
epithelial tissue - covers outside and inside

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5
Q

give two types of glandular tissue the pancreas has

A

1) hormones to control blood sugar
2) some of the digestive enzymes

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6
Q

give some examples of organ systems

A

digestive, circulatory, gas exchange

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7
Q

what do all these organ systems have to be efficient exchange surfaces?

A
  • short diffusion paths
  • rich blood supplies
  • mechanisms for ventilating surfaces or moving materials
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8
Q

role of the digestive system

A

takes the food you eat from insoluble molecules into soluble molecules, then absorbing them into the blood

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9
Q

what does the digestive system include?

A
  • glands, e.g pancreas, salivary glandss
  • stomach
  • liver, producing bile
  • small intestine
  • large intestine
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10
Q

how are villi adapted?

A
  • large surface area to absorb soluble molecules by diffusion/active transport
  • thin wall for short diffusion path
  • good blood supply to carry food molecules away to maintain concentration gradient
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11
Q

what are all carbohydrates made of?

A

units of sugar

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12
Q

how many units of sugar does glucose have?

A

one unit

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13
Q

how many units of sugar does sucrose have?

A

two units linked together

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14
Q

give two examples of simple sugars

A

glucose, sucrose

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15
Q

give examples of complex carbohydrates

A

starch and cellulose made of long chains of simple sugar units that are bonded together

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16
Q

define lipids

A

molecules made of three molecules of fatty acids linked to a molecule of glycerol

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17
Q

define proteins

A
  • made of long chains of amino acids which are folded to form a specific shape
  • other molecules can fit into these specific shapes
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18
Q

what happens if the protein is heated?

A

shape is changed and becomes denatured

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19
Q

give examples of protein functions CHANGE THIS

A

e.g structural components of tissues, such as muscles or hormones, antibodies or enzymes

20
Q

test for carbs; starch

A

yellow-red iodine solutions turns blue-black if starch is present

21
Q

test for carbs; sugars

A

use blue Benedicts solution turns brick red on heating if sugar e.g glucose is present

22
Q

test for protein

A

blue Bierut reagant turns purple if protein is present

23
Q

test for lipids

A

ethanol added to a solution gives a cloudy white layer if lipid is present

24
Q

safety when using ethanol

A

wear eye protection, ethanol is highly flammable and harmful

25
Q

what are chemical reactions in cells controlled by?

A

proteins called enzymes

26
Q

define enzymes

A
  • biological catalysts - speed up reactions
  • shape is vital for function
  • large area called active site where substrate molecule can fit
27
Q

define lock and key theory

A

1) substrate fits into active site
2) substrate splits into products which leave active site
3) enzyme then ready to use again

28
Q

what can enzymes do?

A
  • build large molecules from many smaller ones, e.g building starch from glucose molecules
  • change one molecule into another
  • break down large molecules into smaller ones
29
Q

define metabolism

A

sum of all chemical reactions taking place in a cell or the whole body

30
Q

why do reactions take place faster when it is warmer?

A

at higher temps the molecules move around more quickly and collide with eachother more often, with more energy

31
Q

what happens when temp increases in an enzyme-catalysed reaction?

A
  • the rate of an enzyme catalysed reaction increases
32
Q

what happens if enzymes get too high/

A

stop working and becomes denatured

33
Q

in what way could the active site change?

A

folded shape of protein molecule forming an enzyme is held together by forces, change in pH affects these forces

34
Q

why does enzyme work more efficiently at optimum pH?

A

this is where active site has the best shape

35
Q

what happens if pH is too acidic or alkaline?

A

enzyme becomes denatured so shape of active site changes

36
Q

how are digestive enzymes produced?

A
  • by specialised cells in glands and in the lining of the small intestine
  • pass out of the glands into cavity of the digestive system - work outside the cells
  • come into contact with food so digested
37
Q

what does the digestive system do?

A
  • food into smaller to increase surface area for enzymes to work on
  • mixes food with digestive juices containing enzymes
  • has muscles to move food along
  • areas with different pH
  • absorbs small, soluble food molecules into blood in small intestine
38
Q

define amylase

A
  • a carbohydrase
  • produced by salivary glands, pancreas, small intestine
  • catalyses digestion of starch into sugars in mouth and small intestine
39
Q

define proteases

A
  • produced by stomach, pancreas and small intestine
  • catalyse breakdown of proteins into amino acids in stomach and small intestine
40
Q

define lipase

A
  • produced by pancreas, and small intestine
  • catalyses breakdown of lipids to fatty acids and glycerol
41
Q

what temp do human digestive enzymes work best at?

A

body temp, 37 degrees

42
Q

what conditions do protease enzymes work best at?

A

acidic conditions
- glands in stomach wall produce hydrochloric acid to create very acidic conditions

43
Q

what conditions do other proteases, amylas and lipase work best at?

A

best in small intestine where conditions are slightly alkaline

44
Q

why does the pH of food leaving stomach need to be changed?

A

food leaving stomach is very acidic

45
Q

what does bile do?

A
  • neutralises stomach acid
  • makes conditions in stomach slightly alkaline
  • emulifies fatws to increase surface area of fats for lipase enzymes to act on
46
Q

where is bile stored?

A

gall bladder

gcse biology (17 decks)

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