2. Structure And Functions In Living Organisms Flashcards
1
Q
Test for glucose
A
Benedict’s solution
- add Benedict’s solution to sample of food
- place in water bath 80 degrees for 5 mins
- blue —> brick red/yellow/green
- red has highest conc of sugar
2
Q
Test for starch
A
Iodine test
- add a few drops of orange iodine solution to sample on spotting tile
- orange —> blue/black
3
Q
Protein test
A
Biuret test
- add 2cm3 to food sample and shake
- add equal vol of dilute potassium hydroxide and shake
- add two drops of 1% copper sulfate solution
- blue —> pale purple
4
Q
Test for lipids
A
Emulsion test
- add small vol of absolute ethanol and shake to dissolve any lipids in alcohol
- add equal vol of water
- cloudy white colour forms (emulsion forming)
5
Q
Role of enzymes
A
Biological catalysts in metabolic reactions that speeds up the rate of reaction without being used up itself, provides pathway with a lower activation energy
6
Q
Catalyst
A
Chemical which increases the rate of reaction without being used up itself in the reaction
- remain unchanged so they are free to catalyse more reactions
7
Q
Lock and key theory for enzymes
A
- substrate and enzyme collide
- substrate binds to active site of enzyme
- strains chemical bonds in substrate so the reaction occurs by an alternative pathway with a lower activation energy
- forms products
- products no longer fit onto active site or substrate so they release
- enzyme is unchanged and is free to catalyse the next reaction
8
Q
Factors that affect rate of enzymes:
A
Temperature, pH level, concentration of enzyme/substrate
9
Q
Factors that affect rate of enzymes: temperature
A
As temperature increases the enzyme and substrate have more kinetic energy, they move faster and creates more successful collisions
After the optimum temperature enzymes denature as rate of reaction decreases, active site changes shape and substrate doesn’t fit
10
Q
Factors that affect rate of enzymes: pH level
A
- enzyme function can be affected as it disrupts the forces between different parts of the amino acid chain
- changes active site shape so the protein denatures
- no longer complementary to substrate
11
Q
Factors that affect rate of enzymes: concentration
A
Increase in concentration of substrate or enzyme will speed up the reaction (adding more)
If enzyme becomes too saturated with too much substrate the rate with plateau
At a point it is no longer the limiting factor
12
Q
Practical: investigate how enzyme activity can be affected by changes in temperature
A
C - temperature of water bath
O - vol of starch solution
R - repeat 3x so it’s reliable
M - measure time taken
M - for iodine to stop turning black (blue black from orange iodine)
S - concentration and volume of amylase
S - same concentration of substrate and enzyme
At 60 degrees no digestion/no colour change
13
Q
Diffusion
A
Random movement of molecules from an area of higher concentration to an area of lower concentration across a partially permeable membrane
- allows organisms to gain nutrients in digestive system/gain oxygen in lungs/remove waste products in lungs/kidney
14
Q
Practical: investigate how enzyme activity can be affected by changes in pH
A
C - ph of solution
O - same surface area of photocopier
R - repeat 10x for each pH
M - how long it takes for
M - photocopier to go colourless
S - volume and concentration of enzyme
S - temperature
15
Q
Osmosis
A
Net movement of free water molecules from an area of high water potential to an area of low water potential across a partially permeable membrane
16
Q
Active transport
A
Movement of molecules from an area of low concentration to an area of high concentration using ATP
17
Q
Water potential
A
Measure of concentration of free water molecules in a solution
18
Q
Partially permeable membrane
A
Allows only certain molecules through
19
Q
Four main factors that affect the rate of diffusion/osmosis
A
Temperature, concentration gradient, distance, SA:VOL
20
Q
Factors that affect the rate of diffusion/osmosis: temperature
A
At higher temperatures moleules have more kinetic energy and so move faster
Therefore diffusion occurs faster
21
Q
Factors that affect the rate of diffusion/osmosis: concentration gradient
A
If there’s a very large difference in concentration, molecules with diffuses from the higher to lower concentration quickly
22
Q
Factors that affect the rate of diffusion/osmosis: distance
A
Diffusion takes longer if molecules have to travel further (why cells are small as smaller volume reduces distance)
23
Q
Factors that affect the rate of diffusion/osmosis: SA:VOL
A
A larger surface area speeds up rate of diffusion as there’s more opportunités for molecules to move
SA:V is increased when structures are small
24
Q
Isotonic solution in plant and animal cell
A
Animal - solution outside the cell as the SAME water potential as inside the cell
- no net movement
Flaccid in plant cells
25
Hypotonic solution in animal and plant cell
Animal cell - solution outside the cell has a HIGHER water potential then inside the cell
- net movement of water molecules INTO cell via osmosis
Turgid in plant cell - cytoplasm pushes against cell wall
26
Hypertonic solution in plant and animal cell
Animal - solution outside cell has LOWER water potential then inside the cell
- net movement of free water molecules OUT of the cell via osmosis
Plasmolyzed in plant cell - cytoplasm detached from cell wall
27
What happens to plasmolyzed plant cells
Plant will wilt because there’s not enough water to fill their cells and therefore the cytoplasm shrinks from cell wall
28
Practical: test how the concentration of a sucrose solution affects rate of osmosis
C - sucrose solution concentration
O - same type of potato
R - repeat 3x for each potato cut
M - change in mass of potato
M - with scale
S - same type of potato (same concentration of sucrose)
S - same length of potato ( same SA:VOL)
29
Practical: the effect of surface area to volume ratio on diffusion rate
C - SA:V of agar cubes
O - same agar jelly
R - repeat 3x for each agar cube to ensure reliability
M - length of agar colourless (diffusion occurring)
M - over 2 mins
S - same concentration and volume of solution
S - same temperature of room (can affect diffusion)
30
Other practicals on diffusion/osmosis: visking tube and onion cells
Visking tube - only allows small soluble molecules through so osmosis can occur, can change conc of sucrose solution or temp of water to investigate effect on osmosis (height liquid rises in a set time will increase if osmosis is faster
Onion cells
- soaked in pure water is turgid
- soaked in concentrated sugar/salt solution is plasmolyzed
31
3 cell structures in plants only
Vacuole, cell wall, chloroplasts
32
Nucleus
- controls activity of the cell using DNA
- contains chromosomes
33
Cell membrane
Boundary between cytoplasm and cell
- controls what substances enter and leave the cell
- selectively permeable
- inside wall
34
Cytoplasm
Jelly-like liquid where chemical reactions occur
35
Mitochondria
- produces ATP used for respiration (aerobic)
36
Ribosomes
Site of proteinsynthesis
37
Chloroplasts
Absorb light energy used for photosynthesis
38
Cell wall
Made of cellulose
- gives the plant its shape, keeps it upright
39
Vacuole
Filled with cell sap
- stores dissolved sugars, mineral ions and other substances
40
Differences in animal and plant cell
- Plant has a vacuole, cell wall and chloroplast
Animal vacuole is small and temporary
Plant vacuole is large and permanent
41
Pathway that food takes through alimentary canal
Mouth -> oesophagus -> stomach -> duodenum -> iluem -> colon -> rectum -> anus
42
Egestion
Removal of faeces (undigested food)
43
Excretion
Removal of metabolic waste (e.g. CO2/urea)
44
Ingestion
Taking food in through the mouth and swallowing
45
Digestion
Breaking down large insoluble molecules to smaller soluble molecules
46
Absorption
Movement of small soluble molecules (products of digestion) out of the gut and into the bloodstream by diffusion and active transport
47
Assimilation
Building larger biological molecules from the small soluble molecules in all cells
48
Alimentary canal: mouth
Mechanical digestion - food is crushed/torn/cut by teeth into smaller pieces (increases SA for enzymes and prevents discomfort when swallowing)
Chemical digestion - saliva released by salivary glands (contains salivary amylase, breaks down starch to maltose)
Food is formed into a bolus
49
Alimentary canal: oesophagus
- bolus of food moves from mouth to stomach by muscular contractions called peristalsis
Circular muscles contract behind bolus, moving it along
Longitudinal muscles contract making the oesophagus wider
50
Alimentary canal: stomach
- food is churned around because of muscular contractions -> mechanical digestion
Hydrochloric acid kills pathogens that enter
-> creates optimum pH level (acidic) for pepsin enzyme that converts protein to dipeptides/peptides
51
Alimentary canal: small intenstine
Digestion and absorption occur
Digestion happens in first section -> duodenum
52
Alimentary canal: duodenum (bile)
- final site of chemical digestion
- food mixes with bile which emulsifies food (breaks large droplets into smaller droplets which increases SA for lipase to digest/breakdown fats)
- neutralises stomach acid -> optimum temp for pH (enzymes in duodenum work best at pH 7-8)
53
Alimentary canal: duodenum (enzyme)
Food mixes with enzymes:
Pancreatic amylase
Maltase
Lipase
Trypsin
Peptidase
54
Enzymes in duodenum: pancreatic amylase
Pancreatic amylase converts starch —> maltose
55
Enzymes in duodenum: maltase
Maltase converts maltose —> glucose
56
Enzymes in duodenum: lipase
Lipase converts lipids —> glycerol and 3x fatty acids
57
Enzymes in duodenum: trypsin
Trypsin converts protein —> dipeptides
58
Enzymes in duodenum: peptidase
Peptidase converts dipeptides —> amino acids
59
Alimentary canal: iluem
Absorption of digested food, small soluble molecules absorbed by diffusion
- some like glucose are absorbed via active transport
Contains finger-like projections called villi + microvilli
60
How is the ileum adapted for its function
Microvilli+villi and folds - increase SA which creates more diffusion of digested food
Thin walls - short diffusion distance (one cell thick)
Good blood supply (capillary network) - maintains concentration gradient for diffusion
Has lacteal - absorbs lipids and maintains concentration
61
Alimentary canal: large intenstine
Water removes undigested food -> forms faeces
Faeces is egested, stored in anus
62
Digestion from starch to glucose
Starch -> maltose via amylase
maltose —> glucose via maltase
63
Digestion of proteins
Protein -> amino acids via proteases
64
Digestion of lipids
Lipids -> glycerol + fatty acids
Via lipases
65
How temperature effects enzyme activity
->too low kinetic energy, few collisions as substrate and enzyme dont collide
->increase in temp increases kinetic energy which increases number of collisions, more enzyme subsrate complex formed, rate of reaction increases
->optimum pH, most number of ESC formed, rate is fastest
->enzyme denatured and active site changes shape
66
Cell respiration
The process of breaking down food molecules to release ATP - series of chemical reactions
67
Aerobic respiration
Uses oxygen to break down glucose and release energy and some ATP
68
Aerobic respiration chemical and word equation
Glucose + oxygen —> carbon dioxide + water
C6H12O6 +6 O2 ——>6 CO2+ 6 H2O
69
ATP provides..
..energy for cells
70
Anaerobic respiration
Cells that respire without oxygen -> allows cells to obtain some energy when oxygen is limited
Glucose is not completely broken down - less ATP released
71
Anaerobic respiration word equation in fungi and plants
Glucose —> ethanol + carbon dioxide
72
Anaerobic respiration word equation in animals
Glucose —> lactic acid
If lactic acid builds up it can cause cramps
73
Oxygen debt
Volume of oxygen needed to oxidise the lactic acid
74
Differences in aerobic and anaerobic respiration
Aerobic - completely breaks down glucose, more energy released, uses oxygen
Anaerobic - partially breaks down glucose, less energy released, doesn’t use oxygen
75
Practical: investigate carbon dioxide and heat from respiring seeds -> germinating peas experiment
C - change the content in the flask (germinating/dead seeds)
O - same size/species of seed
R - repeat 3x with both seeds
M - observe change in temperature on the thermometer
M - after 4 days
S - same number of seeds
S - same starting temperature of flasks
76
Practical: investigate carbon dioxide and heat from respiring seeds -> hydrogen carbonate indicator
C - move lamp in different distances
O - same volume of hydrogen carbonate indicator
R - repeat 3 times
M - measure colour change in hydrogen carbonate indicator
M - after 3 hours
S - same amount of organism
S - same volume of hydrogen carbonate
Indicator turns yellow in low light (less CO2)
Indicator turns red/purple in high light (more CO2)
77
Gas exchange system is located
In the thorax (upper part of body)
78
Trachea
Surrounded by c shape rings of cartilage to keep trachea open but make swallowing easier
Splits to form two bronchi
79
Bronchi and bronchioles
Bronchi - tubes lead to lungs, also surrounded by cartilage rings
Bronchioles - bronchi divides/branches into smaller tubes called bronchioles which carry air deep into the thorax
80
Aveoli
Site of gas exchange
- microscopic air sacs at the end of bronchioles
81
Aveoli
Site of gas exchange
- microscopic air sacs at the end of bronchiole
82
Pleural membrane
Lungs are surrounded in it to form a double layer between lungs and thorax
In between the membranes there’s a thin layer of pleural fluid
Forms a air tight seal and prevents the lungs from sticking to the thorax wall (as they inflate+deflate)
83
Ribs
Protects organs in thorax
84
Intercostal muscles
Intercostal muscles between ribs help to connect the bones and help air move in and out lungs
85
Diaphragm
Separates organs or thorax and the abdomen
- domed sheet of muscle and fibrous tissue helps move air into and out lungs
86
Ventilation
Process of moving air in and out the lungs (inhalation and exhalation)
87
Inhalation (diaphragm and intercostal muscles)
Diaphragm contracts -> moves down and flattens
Intercostal muscles contact -> moves ribcage up and out
Volume of thorax increases and air pressure decreases
Air pressure is less than atmospheric pressure causing air to move into lungs
88
Exhalation (diaphragm and intercostal muscles)
Diaphragm relaxes -> moves up and doming
Intercostal muscles relax -> moves rib cage down and in
Volume of thorax decreases and air pressure increases
Air pressure in the thorax is more than atmosphere is pressure, causing air to move out of lungs
89
How are aveoli adapted for gas exchange
Large surface area -> lots of alveoli increases rate of diffusion
High concentration gradient -> surrounded by big capillary network which constantly carries deoxygenated blood and moves oxygenated blood away -> speeds up diffusion
Short distance -> walls of aveoli are only once cell thick and the cell is flattened, gases only need to move a small distance which speeds up diffusion
90
Effects of smoking: carcinogens and chemicals
E.g. tar
Can alter DNA and increase risk of cancer
Chemicals in tobacco destroy cilia, reducing the number
Mucus production increases which cannot be moved out the airways quickly so it builds up and causes risk of infection and smokers cough
- bronchitis from build up of infected mucus in bronchitis
91
Effects of smoking: carbon monoxide
Irreversibly binds to haemogoblin -> forms carboxyhaemogoblin
- reduces amount of oxygen transported by blood
92
Effects of smoking: aveoli and what disease it causes
Smoke reaches aveoli which damages them
Aveoli walls break down and fuse together, forming larger irregular air spaces
- decreases surface area for gas exchange so less oxygen diffuses into blood
- emphysema
93
Coronary heart disease
Fatty deposits form if you have lots of saturated fats in ur diet-> narrows lumen space of artery and reduces blood flow to heart muscle cells
Means that less oxygen is received in heart muscle cells -> aerobic respiration decreases and anaerobic respiration increases -> lactic acid build up -> heart attacks
Smoking increases blood pressure and increases the risk of fatty deposits forming
94
Risk factors that make coronary heart disease more likely
Diet - eating saturated fats increases blood cholesterol and increases fatty deposits
High blood pressure - damages artery lining and increases risk of fatty deposits
Obesity - increases blood pressure and may be linked to poor diet
Lack of exercise - causes high blood pressure
95
Arteries carry blood
Away from the heart at high pressure
96
Veins carry blood
Into the heart at a low pressure
97
Capillaries carry blood
Through all tissues and are site of exchange of materials by diffusion
- tiny vessels, many of them
98
Artery structure
- thick outer wall (Can transport blood at high pressure without bursting)
- thick layer of elastic tissue (allows artery to stretch and recoil to keep blood flowing at high pressure)
- thick layer of muscular tissue (Helps to control flow of blood by widening and narrowing)
99
Vein structure
- fairly thin outer wall (blood flows at lower pressure so thick walls not needed)
- think layer of muscle and elastic tissue (wall can contract to keep blood flowing)
- semilunar valves (prevents blood flowing backwards)
100
Capillary structure
Wall is one cell thick (short distance for diffusion of substances from blood to tissues)
101
Practical: affect of exercise on breathing
C - amount of exercise
O - same age/gender/size/general fitness of students
R - repeat 3x with different amounts of exercise
M - measure change in breathing rate
M - immediately after exercise
S - same type of exercise
S - same temperature of environment
102
Practical: affect of exercise on breathing
C - amount of exercise
O - same age/gender/size/general fitness of students
R - repeat 3x with different amounts of exercise
M - measure change in breathing rate
M - immediately after exercise
S - same type of exercise
S - same temperature of environment
103
Transpiration
The evaporation of water from the surface of a plant
104
4 environmental factors that affect rate of transpiration
Humidity, wind speed, temperature and light intensity
105
Environmental factors that affect rate of transpiration: temperature
Water will evaporate quicker from leaves as water molecules have more kinetic energy -> transpiration will therefore increase as temp increases
106
Environmental factors that affect rate of transpiration: humidity
In humid air there’s lots of water vapour -> smaller concentration gradient so transpiration slows down
Transpiration therefore increases if humidity decreases
107
Environmental factors that affect rate of transpiration: wind speed
In moving air, water vapour will be blown away from leaf which speed sup transpiration
Transpiration therefore increases as wind speed increase
108
Environmental factors that affect rate of transpiration: light intensity
In daylight stomata of leaf opens to supply CO2 for photosynthesis
Allows more water to diffuse out of leaves and into atmosphere
109
Practical: role of environmental factors affecting rate of transpiration in leafy shoot
E.g. light
C - change intensity of light
O - plants of same species
R - repeat for each light intensity
M - measure distance travelled by bubble in potometer
M - in 30 mins
S - control the temperature/wind speed/humidity of environment
Black bag so there’s no photosynthesis -> stomata closes -> decrease in rate of transpiration
110
Practical: role of environmental factors affecting rate of transpiration in leafy shoot
E.g. wind/temp
Wind -> use fan, blows away water droplets and increases rate of transpiration as it creates a concentration gradient
Temperature -> use hairdryer, more evaporation, more kinetic energy with movement of water droplets, increases rate of transpiration
111
Rate of transpiration equation
Rate of transpiration = distance moved by air bubble (M) / time (min)
112
Why does breathing rate increasing during excerise
As a response to increased concentration of carbon dioxide in the blood -> excrete carbon dioxide more rapidly -> supplies more oxygen to muscles -> more aerobic respiration
113
Chemical element in carbohydrate
Made of carbon, hydrogen, oxygen
(CHO)
114
Chemical element in lipids (fats)
Made of carbon, hydrogen, oxygen
(CHO)
115
Chemical element in proteins
Made of carbon, hydrogen, oxygen and nitrogen
(CHON)
116
Carbohydrates are broken down in
a chemical reaction (respiration) to release energy in the form ATP
117
Structure of carbohydrate as large molecules made from smaller units
Simple sugars —> glucose and fructose
Two sugar molecule —> Glucose + fructose = sucrose
Complex carbohydrates —> starch (used to store glucose in plants) and glycogen (used to store glucose in animals ans fungi), less soluble and have less effect on water movement in and out of cells
118
Structure of lipids as large molecules made from smaller units + function
Made of 3 fatty acids joined to glycerol molecule
Functions: energy storage, thermal insulation, electrical insulation, buoyancy
119
Structure of proteins as large molecules made from smaller units + function
Made of many amino acids joined together
Functions: structural molecules like collagen and keratin, hormones, combating disease - antibodies, transport of haemogoblin
120
Levels of organisation in organisms and examples
Organelles, cells, tissues, organs and systems + organisms
Mitochondria, plant cell, muscle, heart, cardiovascular system, human
