2. Structure And Functions In Living Organisms Flashcards
Test for glucose
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
Test for starch
Iodine test
- add a few drops of orange iodine solution to sample on spotting tile
- orange —> blue/black
Protein test
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
Test for lipids
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)
Role of enzymes
Biological catalysts in metabolic reactions that speeds up the rate of reaction without being used up itself, provides pathway with a lower activation energy
Catalyst
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
Lock and key theory for enzymes
- 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
Factors that affect rate of enzymes:
Temperature, pH level, concentration of enzyme/substrate
Factors that affect rate of enzymes: temperature
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
Factors that affect rate of enzymes: pH level
- 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
Factors that affect rate of enzymes: concentration
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
Practical: investigate how enzyme activity can be affected by changes in temperature
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
Diffusion
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
Practical: investigate how enzyme activity can be affected by changes in pH
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
Osmosis
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
Active transport
Movement of molecules from an area of low concentration to an area of high concentration using ATP
Water potential
Measure of concentration of free water molecules in a solution
Partially permeable membrane
Allows only certain molecules through
Four main factors that affect the rate of diffusion/osmosis
Temperature, concentration gradient, distance, SA:VOL
Factors that affect the rate of diffusion/osmosis: temperature
At higher temperatures moleules have more kinetic energy and so move faster
Therefore diffusion occurs faster
Factors that affect the rate of diffusion/osmosis: concentration gradient
If there’s a very large difference in concentration, molecules with diffuses from the higher to lower concentration quickly
Factors that affect the rate of diffusion/osmosis: distance
Diffusion takes longer if molecules have to travel further (why cells are small as smaller volume reduces distance)
Factors that affect the rate of diffusion/osmosis: SA:VOL
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
Isotonic solution in plant and animal cell
Animal - solution outside the cell as the SAME water potential as inside the cell
- no net movement
Flaccid in plant cells
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
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
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
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)
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)
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
3 cell structures in plants only
Vacuole, cell wall, chloroplasts
Nucleus
- controls activity of the cell using DNA
- contains chromosomes
Cell membrane
Boundary between cytoplasm and cell
- controls what substances enter and leave the cell
- selectively permeable
- inside wall
Cytoplasm
Jelly-like liquid where chemical reactions occur
Mitochondria
- produces ATP used for respiration (aerobic)
Ribosomes
Site of proteinsynthesis
Chloroplasts
Absorb light energy used for photosynthesis
Cell wall
Made of cellulose
- gives the plant its shape, keeps it upright
Vacuole
Filled with cell sap
- stores dissolved sugars, mineral ions and other substances
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
Pathway that food takes through alimentary canal
Mouth -> oesophagus -> stomach -> duodenum -> iluem -> colon -> rectum -> anus
Egestion
Removal of faeces (undigested food)
Excretion
Removal of metabolic waste (e.g. CO2/urea)
Ingestion
Taking food in through the mouth and swallowing
Digestion
Breaking down large insoluble molecules to smaller soluble molecules
Absorption
Movement of small soluble molecules (products of digestion) out of the gut and into the bloodstream by diffusion and active transport
Assimilation
Building larger biological molecules from the small soluble molecules in all cells
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
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
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
Alimentary canal: small intenstine
Digestion and absorption occur
Digestion happens in first section -> duodenum
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)
Alimentary canal: duodenum (enzyme)
Food mixes with enzymes:
Pancreatic amylase
Maltase
Lipase
Trypsin
Peptidase
Enzymes in duodenum: pancreatic amylase
Pancreatic amylase converts starch —> maltose
Enzymes in duodenum: maltase
Maltase converts maltose —> glucose
Enzymes in duodenum: lipase
Lipase converts lipids —> glycerol and 3x fatty acids
Enzymes in duodenum: trypsin
Trypsin converts protein —> dipeptides
Enzymes in duodenum: peptidase
Peptidase converts dipeptides —> amino acids
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
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
Alimentary canal: large intenstine
Water removes undigested food -> forms faeces
Faeces is egested, stored in anus
Digestion from starch to glucose
Starch -> maltose via amylase
maltose —> glucose via maltase
Digestion of proteins
Protein -> amino acids via proteases
Digestion of lipids
Lipids -> glycerol + fatty acids
Via lipases
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
Cell respiration
The process of breaking down food molecules to release ATP - series of chemical reactions
Aerobic respiration
Uses oxygen to break down glucose and release energy and some ATP
Aerobic respiration chemical and word equation
Glucose + oxygen —> carbon dioxide + water
C6H12O6 +6 O2 ——>6 CO2+ 6 H2O
ATP provides..
..energy for cells
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
Anaerobic respiration word equation in fungi and plants
Glucose —> ethanol + carbon dioxide
Anaerobic respiration word equation in animals
Glucose —> lactic acid
If lactic acid builds up it can cause cramps
Oxygen debt
Volume of oxygen needed to oxidise the lactic acid
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
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
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)
Gas exchange system is located
In the thorax (upper part of body)
Trachea
Surrounded by c shape rings of cartilage to keep trachea open but make swallowing easier
Splits to form two bronchi
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
Aveoli
Site of gas exchange
- microscopic air sacs at the end of bronchioles
Aveoli
Site of gas exchange
- microscopic air sacs at the end of bronchiole
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)
Ribs
Protects organs in thorax
Intercostal muscles
Intercostal muscles between ribs help to connect the bones and help air move in and out lungs
Diaphragm
Separates organs or thorax and the abdomen
- domed sheet of muscle and fibrous tissue helps move air into and out lungs
Ventilation
Process of moving air in and out the lungs (inhalation and exhalation)
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
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
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
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
Effects of smoking: carbon monoxide
Irreversibly binds to haemogoblin -> forms carboxyhaemogoblin
- reduces amount of oxygen transported by blood
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
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
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
Arteries carry blood
Away from the heart at high pressure
Veins carry blood
Into the heart at a low pressure
Capillaries carry blood
Through all tissues and are site of exchange of materials by diffusion
- tiny vessels, many of them
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)
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)
Capillary structure
Wall is one cell thick (short distance for diffusion of substances from blood to tissues)
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
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
Transpiration
The evaporation of water from the surface of a plant
4 environmental factors that affect rate of transpiration
Humidity, wind speed, temperature and light intensity
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
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
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
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
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
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
Rate of transpiration equation
Rate of transpiration = distance moved by air bubble (M) / time (min)
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
Chemical element in carbohydrate
Made of carbon, hydrogen, oxygen
(CHO)
Chemical element in lipids (fats)
Made of carbon, hydrogen, oxygen
(CHO)
Chemical element in proteins
Made of carbon, hydrogen, oxygen and nitrogen
(CHON)
Carbohydrates are broken down in
a chemical reaction (respiration) to release energy in the form ATP
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
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
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
Levels of organisation in organisms and examples
Organelles, cells, tissues, organs and systems + organisms
Mitochondria, plant cell, muscle, heart, cardiovascular system, human
