Structure and functions in living organisms Flashcards
1
Q
What role do enzymes play in metabolic reactions?
A
-biological catalysts that speed up the rate of metabolic reactions (like digestion) by allowing substrates to bind to their active sites, breaking them down into products.
2
Q
What is the function of an enzyme’s active site?
A
-where substrates bind, allowing the enzyme to catalyse the reaction and produce products.
3
Q
What is the function of amylase/maltase?
A
Breaks down starch —> glucose
4
Q
What is the function of protease?
A
Breaks down proteins —> amino acids
5
Q
What is the function of lipase?
A
Breaks down lipids —> fatty acids & glycerol
6
Q
What happens to enzyme activity as temperature increases towards the optimum?
A
The rate of enzyme activity increases.
7
Q
Why does enzyme activity increase with rising temperature?
A
-Enzymes & substrates gain kinetic energy, moving & vibrating faster
-Leading to more frequent successful enzyme-substrate collisions.
8
Q
How does increased kinetic energy affect enzyme-substrate interactions?
A
It allows more frequent successful collisions, increasing the rate at which substrates are broken down.
9
Q
What happens to enzymes when temperatures exceed the optimum?
A
Enzymes denature
10
Q
Why do enzymes denature at high temperatures?
A
-High temperatures cause bonds within the enzyme to vibrate more
-Increasing the chance of bond breakage.
11
Q
A
-It changes the shape and structure of the active site
-Preventing the substrate from binding properly.
12
Q
What is the consequence of enzyme denaturation for metabolic reactions?
A
Metabolic reactions cannot take place because the enzyme loses its function.
13
Q
What is the optimum pH for most enzymes?
A
The optimum pH for most enzymes is 7.
14
Q
What is the optimum pH for enzymes found in the stomach?
A
Around pH 2, as stomach enzymes work in acidic conditions.
15
Q
What is the optimum pH for enzymes found in the duodenum?
A
Around pH 8 or 9, since these enzymes work in alkaline conditions.
16
Q
What happens if the pH is too high or too low for an enzyme?
A
-The bonds holding the amino acid chain together may be disrupted or destroyed.
-Changing the shape of the active site, so the substrate can no longer fit into it
-Reducing the rate of activity
17
Q
How does pH affect the shape of an enzyme’s active site?
A
If the pH moves too far from the optimum, the active site’s shape changes, preventing the substrate from fitting.
18
Q
What happens to enzyme activity if the substrate can no longer fit the active site?
A
The rate of enzyme activity decreases.
19
Q
What occurs if the pH shifts too far from the enzyme’s optimum?
A
The enzyme denatures and activity stops.
20
Q
How does the pH graph for enzymes in the duodenum typically look?
A
It shows a peak around pH 8 or 9, with activity dropping at lower or higher pH levels.
21
Q
What effect does optimal pH have on enzyme-substrate collisions?
A
-More frequent successful collisions occur between enzymes and substrates.
-This increases the rate of substrate breakdown and enzyme activity.
22
Q
Design an experiment investigating how enzyme activity can be affected by changes in temperature
A
C - Changing the temperature in each repeat
O - Not relevant, no organisms
R - Repeat experiment several times to ensure reliable results
M1 - Measure the time taken
M2 - for the iodine to stop turning black
S - Same concentration and volume of starch solution, iodine and amylase used in the investigation
23
Q
Explain the results of investigating the effect of temperature on enzyme activity
A
-Amylase is an enzyme which breaks down starch
-The quicker the reaction is completed, the faster the enzyme is working
-Optimum temperature- the iodine stopped turning blue-black the fastest (because the enzyme is working at its fastest rate and has digested all the starch)
-Colder temperatures (below optimum), the iodine took a longer time to stop turning blue-black
(because the amylase enzyme is working slowly due to low kinetic energy and few collisions between the amylase and the starch)
-Hotter temperatures (above optimum) the iodine turned blue-black throughout the whole investigation (because the amylase enzyme has become denatured and so can no longer bind with the starch or break it down)
24
Q
What is the method for investigating how enzyme activity can be affected by changes in temperature?
A
1.Add 5cm3 starch solution to a test tube & heat to a set temperature using beaker of water with a Bunsen burner
2.Add a drop of Iodine to each of the wells of a spotting tile
3.Use a syringe to add 2cm3 amylase to the starch solution & mix well
4.Every minute, transfer a droplet of solution to a new well of iodine solution (which should turn blue-black)
5.Repeat this transfer process until the iodine solution stops turning blue-black (this means the amylase has broken down all the starch)
6.Record the time taken for the reaction to be completed
7.Repeat the investigation for a range of temperatures (from 20°C to 60°C)
25
What is the method for investigating the effect on temperature on diffusion in beetroot? (investigating diffusion using living and non-living systems)
1.Using a knife, cut 2 equally-sized cubes of beetroot (or a cork borer)
2.Rinse the beetroot pieces
-To remove any pigment released during cutting
3.Put 5 cm3 of water into 2 test tubes labelled A and B
4.Keep test tube A at room temperature and transfer test tube B to a hot water bath at 90℃
5.Leave the test tubes for 2 minutes, then add a piece of beetroot into each test tube
6.After 10 minutes, observe the colour of the liquid in both test tubes
26
Design an experiment investigating diffusion using living and non-living systems
C - Changing the temperature of the environment
O - Cubes taken from same beetroot or beetroot of the same age
R - Repeat experiment several times to ensure reliable results
M1 - Observe the colour change of the liquid
M2 - after 10 minutes
S - Same volume of water used
Same dimensions of beetroot cubes
Each cube must be blotted before it is weighed each time
27
What are the results for investigating the effect of temperature on diffusion in beetroot?
-The higher temperature, more of the pigment has leaked out of the beetroot
-The cell membrane of the beetroot cells has become damaged so more pigment can leak out
-At higher temperatures, particles have more kinetic energy, this results in the faster movement of particles compared to when they have less energy
28
What are the limitations for investigating the effect of temperature on diffusion in beetroot?
-Beetroot size and shape variation affects tissue quantity.
Solution: Precisely cut beetroot, repeat for accuracy.
-Beetroot pigment concentrations vary.
Solution: Repeat with different beetroot parts, calculate mean.
-Testing a wider temperature range enhances reliability.
Solution: Use 5 test tubes at various temperatures.
-Subjective color observation complicates comparison.
Solution: Employ a colorimeter for objective measurement.
29
What is the method for investigating osmosis in cells?
1.Prepare a range of sucrose (sugar) solutions ranging from 0 Mol/dm3 (distilled water) to 1 mol/dm3
2.Set up 6 labelled test tubes with 10cm3 of each of the sucrose solutions
3.Using the knife, cork borer and ruler, cut 6 equally-sized cylinders of potato
4.Blot each one with a paper towel and weigh on the balance
5.Put 1 piece into each concentration of sucrose solution
6.After 4 hours, remove them, blot with paper towels and reweigh them
30
What are the limitations of investigating osmosis in cells?
-Variations in potato cylinder sizes may compromise result reliability.
Solution: Repeat the investigation with multiple potato cylinders for each sucrose concentration. This helps identify and discard any anomalous results when calculating the mean.
31
Design an experiment investigating osmosis in cells (potato cells)
C - Changing the concentration of sucrose solution
O - Potato cylinders taken from the same potato or potatoes of the same age
R - Repeat experiment several times to ensure reliable results
M1 - Measure the change in mass of the potato cylinders
M2 - after 4 hours
S - sucrose used
Same dimensions of potato cylinders
Each cube must be blotted before it is weighed each time
32
What are the results for investigating osmosis in potato cells?
-Potato in distilled water gains most mass due to high water potential gradient from water to cells.
-Water moves into potato cells via osmosis, increasing turgor pressure and making them turgid, resulting in firm potato cylinders.
-Highest sucrose concentration causes most mass loss in potato due to greater concentration gradient: potato cells (higher water potential) to sucrose solution (lower water potential).
-Water moves out via osmosis, making cells flaccid, causing cylinder to feel floppy.
-Cells from this potato cylinder might show plasmolysis under the microscope, indicating the cell membrane has pulled away from the cell wall.
33
Diffusion
The movement of particles from a high to low concentration.
34
Active transport
The movement of particles from a low to high concentration.
35
Osmosis
The movement of water from an area of high water potential (high water concentration) to an area of low water potential (low water concentration) across a partially permeable membrane.
36
How does concentration gradient affect the rate of movement of substances into and out of the cells?
-As concentration gradient increases, the rate of movement of substances into and out of cells will increase
-because a stronger concentration gradient is present, hence increasing the rate of movement of substance
37
How does surface area to volume ratio affect the rate of movement of substances into and out of the cells?
-As the surface area to volume ratio (SA:V) increases, the rate of movement of substances into and out of cells will increase
-because there is a larger surface area in which substances can move through, (hence increasing the rate of movement of substance)
38
How does temperature affect the rate of movement of substances into and out of the cells?
As temperature increases, the rate of movement of substances into and out of cells will increase
-because particles gain more kinetic energy and so will move faster (hence increasing the rate of movement of substance)
39
How does distance affect the rate of movement of substances into and out of the cells?
-The smaller the distance molecules have to travel, the faster the transport will occur.
-This is why blood capillaries and alveoli have walls that are one cell thick.
-Thinner walls ensure the rate of diffusion is as fast as possible.
40
Organelles
A component within a cell that carries out a specific task
41
Cells
Basic functional and structural units in a living organism
42
Tissues
A group of cells of similar structure working together to perform a particular function
43
Organs
Made from a group of different tissues working together to perform a particular function
44
Organ systems
Made from a group of organs with related functions, working together to perform body functions within the organism
45
What is the order of levels of organisation?
Organelles, cells, tissues, organs, organ systems
46
Nucleus
-Controls the activity of the cell (by making proteins)
-Contains the chromosomes - strands of DNA which carry the genes (each gene codes for a protein)
47
Cell membrane
-Boundary between the cytoplasm and the cell's surroundings
-Controls what
substances enter and leave the cell (selectively permeable)
48
Cytoplasm
-Jelly-like liquid where chemical reactions occur
49
Mitochondria
-Carries out some reactions of aerobic respiration, producing ATP (energy
carrier molecule)
50
Ribosomes
-Synthesise (assemble) proteins from amino acids
51
Chloroplasts
-Absorb light energy and use it to carry out the chemical reactions of photosynthesis, making biological molecules for plant cells
52
Vacuole
-Filled with a watery liquid called cell sap
-stores dissolved sugars, mineral ions and other substances.
53
Cell wall
-Made of cellulose (a carbohydrate) in plants
-Helps to keep plant cells in a fixed shape (and so keeps the plant upright)
54
What are the differences between animal and plant cells?
Only plants have large permanent vacuole, cell wall and chloroplasts
55
What is the structure and function of the mouth?
-Where mechanical digestion takes place (teeth chew food to break it into smaller pieces and increase its surface area to volume ratio)
-Amylase enzymes in saliva start digesting starch into maltose
-The food is shaped into a bolus (ball) by the tongue and lubricated in saliva so it can be swallowed easily
56
What is the structure and function of the oesophagus?
-Tube that connects mouth to the stomach
-Where the food bolus goes after being swallowed
-Wave-like contractions will take place to push the food bolus down without relying on gravity
57
What is the structure and function of the stomach?
-Food is mechanically digested by churning actions (while protease enzymes start to chemically digest proteins)
-HCL is present to kill bacteria in food & provide optimum pH for protease enzymes to work
58
What is the structure and function of the small intestine? (Duodenum)
-Where the food coming out of the stomach finishes being digested by enzymes produced here and also secreted from the pancreas
-pH of small intenstine is slightly alkaline (pH 8-9)
59
What is the structure and function of the small intestine? (Ileum)
-Where the absorption of digested food molecules takes place
-The ileum is long and lined with villi to increase the surface area over which absorption can take place
-pH of small intenstine is slightly alkaline (pH 8-9)
60
What is the structure and function of the large intestine?
-Water is absorbed from remaining material in the colon (to produce faeces)
-Faeces is stored in the rectum and removed through the anus
61
What is the structure and function of the pancreas?
-Produces all three types of digestive enzymes: AMYLASE, PROTEASE, and LIPASE
-Secretes enzymes in an alkaline fluid into the duodenum (for digestion to raise pH of fluid coming out of the stomach)
62
Know that ATP provides energy for cells
-Respiration releases energy from glucose
-The energy is transferred via the molecule ATP
-ATP required for living processes to occur within cells & organisms (e.g. active transport)
63
Describe the differences between aerobic and anaerobic respiration?
-oxygen needed for aerobic & not anaerobic
-aerobic produces lots of ATP, whereas anaerobic produces a small amount
-products of both are different
64
What is the word equation for anaerobic respiration in animals?
Glucose —-> Lactic acid
65
What is the word equation for anaerobic respiration in plants?
Glucose —-> ethanol + carbon dioxide
66
What is the word and balanced chemical symbol equation for aerobic respiration in living organisms?
Glucose + Oxygen —-> Carbon dioxide + Water
C6H12O6 + 6O2 —-> 6CO2 + 6H2O
67
How does the process of respiration produce ATP in living organisms?
-Respiration is carried out in all living organisms
-Energy is released from glucose, either in: the presence of oxygen (AEROBIC RESPN) or the absence of oxygen (ANAEROBIC RESPN)
-In aerobic, reactions result in production waste products (CO2 + H2O)
-Energy transferred in the form of ATP
68
What specific adaptations do villi have for rapid absorption?
-Large surface area with microvilli that further increase surface available for absorption.
-Short diffusion distance; walls of villi are one cell thick.
-Steep concentration gradient; well-supplied with a network of blood capillaries.
69
What role does peristalsis play in the small intestine?
Mixes together food and enzymes.
Keeps food moving along the alimentary canal.
70
What are the functions of villi in the small intestine
-Transport: Lacteals carry fatty acids & glycerol to lymph.
-Assistance in digestion: Enzymes in villi aid chemical digestion.
-Movement: Villi help mix food with enzymes and move it along.
71
What adaptations do villi have for rapid absorption?
-Large surface area: Increased by microvilli.
-Short diffusion distance: Wall is one cell thick.
-Steep concentration gradient: Well-supplied with blood capillaries.
72
What is the method for investigating (the evolution of CO2) respiration using germinating seeds?
1.Measure 10 cm³ of hydrogen carbonate indicator into 3 boiling tubes.
2.Add a layer of cotton wool in each tube.
3.Place 10 germinating seeds in Tube A, 10 boiled/dead seeds in Tube B, and 10 glass beads in Tube C.
4.Seal each tube with a rubber bung.
5.Observe the color of the indicator after 3 hours.
73
Design an experiment to investigate the evolution of carbon dioxide from respiring seeds or other suitable living organisms
C: Change the type of organism (germinating seeds vs. boiled/dead seeds vs. glass beads).
O: Use germinating seeds, boiled/dead seeds, and glass beads.
R: Conduct multiple trials to ensure reliable results.
M: Measure the color change in hydrogen carbonate indicator after 3 hours.
S: Same temperature, same volume of indicator
74
What are the expected results when investigating the production of carbon dioxide during respiration?
-Tube A: Turns yellow – Germinating seeds are actively respiring and producing CO₂.
-Tube B: Stays orange – Boiled/dead seeds do not respire or produce CO₂.
-Tube C: Stays orange – Glass beads contain no living material and do not produce CO₂.
75
Thorax
Part of body between Neck and Abdomen
76
Ribs
-Protects internal organs like the heart and lungs.
77
Intercostal muscles
-Muscles between the ribs which control their movement causing inhalation and exhalation
78
Diaphragm
-Sheet of muscle under the lungs
-Contracts to increase thorax volume (inhalation) & relaxes to decrease volume (exhalation).
79
Trachea
-Windpipe that connects the mouth/nose to the lungs.
80
Bronchi (pl)
-Large tubes branching off the trachea with 1 bronchus (sin) for each lung
81
Bronchioles
-Bronchi split to form smaller tubes called bronchioles in the Lungs connected to alveoli
82
Alveoli
-Tiny air sacs where gas exchange takes place
83
Pleural membrane
-Thin, moist membrane lining the outside of the lungs
-Provides lubrication to reduce friction during breathing
-Attaches the lungs to the chest cavity to ensure they follow chest movements
84
Inhalation
- Diaphragm contracts & flattens
- External intercostal muscles contract, pulling ribs up & out
- Chest cavity (thorax) volume increases
- Air pressure inside the lungs decreases (relative to outside air)
- Air is drawn into the lungs
85
Exhalation
- Diaphragm relaxes, moving upwards into a domed shape
- External intercostal muscles relax, allowing ribs to move down & in
- Chest cavity (thorax) volume decreases
- Air pressure inside the lungs increases (relative to outside air)
- Air is forced out of the lungs
86
What does smoking cause?
-chronic obstructive lung disease (COPD)
-coronary heart disease
-increased risks of several different types of cancer, including lung cancer
87
Coeliac disease is an autoimmune condition where cells of the immune system attack and destroy villi in the small intestine. Explain how this will affect the process of absorption. (2)
* Fewer villi will lead to a decrease in surface area of the ileum/small intestine
* This results in a decrease in the rate of absorption
88
What chemicals are in cigarettes?
-Tar - a carcinogen (a substance that causes cancer)
-Nicotine - an addictive substance which also narrows blood vessels
-Carbon monoxide - reduces the oxygen-carrying capacity of the blood
89
Nicotine
-Nicotine narrows blood vessels leading to an increased blood pressure
-It also increases heart rate
-Both of these effects can cause blood clots to form in the arteries leading to heart attack or stroke
90
Carbon monoxide
-binds to haemoglobin, reducing oxygen capacity in blood.
-makes breathing harder, needing more frequency & depth to get enough oxygen.
-strains heart, increasing risk of heart disease and strokes.
91
Tar
TAR
- Carcinogen linked to increased cancer risk in lungs.
- Contributes to COPD (occurs when chronic bronchitis and emphysema) (two different diseases which are frequently linked to smoking) occur together
92
Chronic Bronchitis
-Stimulates goblet cells and mucus glands, leading to mucus overproduction.
- Destroys cilia, leading to mucus buildup, blocking bronchioles, causing infections.
- Resulting smoker's cough attempts to clear mucus.
93
Emphysema
CAUSE: Frequent infections, often due to mucus build-up in smokers' lungs
PROCESS: Phagocytes release elastase, breaking down elastic fibers in alveoli
Alveoli lose elasticity and burst, reducing surface area for gas exchange
SYMPTOMS: Breathlessness, wheezing, and need for constant oxygen supply
94
Design an experiment to investigate the evolution of heat from respiring seeds or other suitable living organisms
Change: Change the content of the flasks (germinating seeds or dead seeds).
Organisms: Use seeds of the same age, size, and species.
Repeat: Repeat the investigation several times for reliability.
Measurement 1: Observe the change in temperature on the thermometer.
Measurement 2: Record temperature after 4 days.
Same: Control the number of seeds, starting temperature, and flask material/size.
95
What are the expected results of the heat production experiment?
-Flask B (germinating seeds) shows an increase in temperature.
-Flask A (dead seeds) remains at room temperature.
-Conclusion: Germinating seeds are respiring, producing heat; dead seeds are not respiring.
96
What is the method for demonstrating heat production in seeds?
1.Set up two vacuum flasks:
Flask A: Contains dead seeds.
Flask B: Contains germinating seeds.
2.Plug the tops with cotton wool & hold the thermometer in place.
3.Invert the flasks & record the initial temperature.
4. After 4 days, record the final temperature.
97
What are the limitations of investigating the effect of exercise on breathing?
Difficulty controlling variables:
- Ensure students are similar in size, fitness, age, and gender
- Provide each with the same meal before exercise
Challenges in replicating activity:
- Use exercise types with easier intensity control (e.g., treadmill running, cycling with specific power output)
Variability and quick changes in breathing rate:
- Start counting immediately when the time interval begins
- Measure for a short duration (e.g., 15 seconds) and multiply to calculate breaths per minute
Potential fatigue during investigation:
- Allow significant rest breaks between exercises
- Avoid prolonged periods of exercise
98
What are the results for investigating the effect of exercise on breathing?
Frequency of breathing increases when exercising:
-because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand
-cannot meet the energy demand they will also respire anaerobically, producing lactic acid
After exercise has finished, the breathing rate remained elevated for a period of time:
-because the lactic acid that has built up in muscles needs to be removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions
-can only be removed by combining it with oxygen - this is known as ‘repaying the oxygen debt’
-can be tested by seeing how long it takes after exercise for the breathing rate to return to normal
The longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt that needs to be repaid
99
What is the method for investigating the effect of exercise on breathing?
1.Measure resting breathing rate for student A by counting breaths for 15 seconds and multiplying by 4; repeat for accuracy and calculate average.
2.Student A exercises for a minimum of 4 minutes.
3.Post-exercise, count breaths for 15 seconds and multiply by 4 to determine breathing rate per minute.
4.Compare post-exercise breathing rate to resting rate to assess change.
5.Repeat post-exercise breathing rate measurement every minute for 5 minutes.
6.Repeat entire process for student B.
7.After a rest period, repeat investigation for both students.
100
Design an experiment investigating the effect of exercise and release of carbon dioxide on breathing
Change - whether the student has exercised or not
Organisms - students should be of the same age, gender, size and general fitness
Repeat - Repeat investigation several times to ensure reliable results
Measurement 1 - the change in breathing rate
Measurement 2 - immediately after exercise & each minute for the subsequent 5 minutes
Same - Same type of exercise carried out
Same temperature of the environment
Same food intake of the students prior to the investigation
101
Describe how water is lost from a plant by transpiration? (3)
-Water evaporates
-From the surface of mesophyll cells (in the leaf)
-Into the air spaces (in the leaf)
-Water vapour diffuses out the leaf
-Through the stomata
102
Transpiration
The loss of water by evaporation from the leaves of plants
103
What is water needed in the leaves for?
-Photosynthesis
-Transport of mineral ions
-Structural support
104
How is the rate of transpiration is affected by changes in wind speed?
More- good airflow removes water vapour from the air surrounding the leaf
-sets up a concentration gradient between the leaf and the air, -increasing water loss
105
How is the rate of transpiration is affected by changes in temperature?
Less - humidity is a measure of moisture (water vapour) in the air; -when the air is saturated with water vapour
-concentration gradient is weaker so less water is lost
106
How is the rate of transpiration is affected by changes in light intensity?
More - guard cells are responsive to Light intensity
-when it is high they are turgid
-the stomata open allowing water to be lost
107
How is the rate of transpiration is affected by changes in humidity?
Less - humidity is a measure of moisture (water vapour) in the air
-when the air is saturated with water vapour
-the concentration gradient is weaker so less water is lost
108
What is the method for investigating the role of environmental factors in determining the rate if transpiration from a leafy shoot?
1.Cut a slant on the stem of the plant when its underwater
2.Make sure there are no air leaks, using vaseline to seal the gaps
3.Reset an air bubble in the tube
4.Measure how far the bubble moves over an equal amount of time
5.Repeat experiment 3x (e.g. with and without fan for wind speed)
6.Calculate water loss using equation:
Rate of transpiration= distance moved by air bubble (m)/ time (m)
109
What are the results for investigating the role of different environmental factors (light intensity) in determining the rate if transpiration from a leafy shoot?
-As light intensity increases, the rate of transpiration increases
-shown by the bubble moving a greater distance in the 30 minute time period when the lamp was placed closer to the leaf
-Transpiration rate increases with light intensity because more stomata tend to be open in bright light in order to maximise photosynthesis
-The more stomata that are open, the more water can be lost by evaporation and diffusion through the stomatal pores
110
What are the limitations for investigating the role of environmental factors in determining the rate if transpiration from a leafy shoot?
-The potometer equipment has a leak
Solution: Ensure that all equipment fits together rightly around the rubber bungs and assemble underwater to help produce a good seal
-The plant cutting has a blockage
Solution: Cut the stem underwater and assemble equipment underwater to minimise opportunities for air bubbles to enter the xylem
-The potometer has shown no change during the experiment
Solution: Use the plant cuttings as soon as they have been cut, transpiration rates may slow down when the cuttings are no longer fresh
111
Design an experiment investigating the role of light intensity in determining the rate if transpiration from a leafy shoot
Change - change the intensity of the light (Placing lamp at variable distance from plant)
Organisms - plants used in each repeat should be the same species, size, age, number of leaves
Repeat - repeat the investigation several times to ensure reliable results
Measurement 1 - the distance travelled by the bubble
Measurement 2 - in 30 minutes (calculate the rate of transpiration)
Same -Same temperature
Same wind speed
Same humidity of environment
112
Design an experiment investigating the role of temperature in determining the rate if transpiration from a leafy shoot
Change - change the temperature (heater)
Organisms - plants used in each repeat should be the same species, size, age, number of leaves
Repeat - repeat the investigation several times to ensure reliable results
Measurement 1 - the distance travelled by the bubble
Measurement 2 - in 30 minutes (calculate the rate of transpiration)
Same -Same light intensity
Same wind speed
Same humidity of environment
113
Design an experiment investigating the role of temperature in determining the rate if transpiration from a leafy shoot
Change - change the temperature (heater)
Organisms - plants used in each repeat should be the same species, size, age, number of leaves
Repeat - repeat the investigation several times to ensure reliable results
Measurement 1 - the distance travelled by the bubble
Measurement 2 - in 30 minutes (calculate the rate of transpiration)
Same -Same light intensity
Same wind speed
Same humidity of environment
114
Design an experiment investigating the role of humidity in determining the rate if transpiration from a leafy shoot
Change - humidity of environment (Encasing plant in plastic bag with variable levels of vapour)
Organisms - plants used in each repeat should be the same species, size, age, number of leaves
Repeat - repeat the investigation several times to ensure reliable results
Measurement 1 - the distance travelled by the bubble
Measurement 2 - in 30 minutes (calculate the rate of transpiration)
Same -Same light intensity
Same wind speed
Same temperature
115
Design an experiment investigating the role of wind movement in determining the rate if transpiration from a leafy shoot
Change - wind speed (fan)
Organisms - plants used in each repeat should be the same species, size, age, number of leaves
Repeat - repeat the investigation several times to ensure reliable results
Measurement 1 - the distance travelled by the bubble
Measurement 2 - in 30 minutes (calculate the rate of transpiration)
Same -Same light intensity
Same humidity
Same temperature
116
Rate of transpiration?
Rate of transpiration= Distance moved by air bubble (m)/ Time (min)
117
What chemical elements are present in carbohydrates, lipids and proteins?
Carbohydrates: Carbon, Hydrogen, Oxygen
Lipids: Carbon, Hydrogen, Oxygen
Proteins: Carbon, Hydrogen, Oxygen, Nitrogen
118
Explain why a blockage to the coronary arteries may be fatal (3 marks)
-Coronary arteries supply the heart cells/ tissue with blood
-Blood carries oxygen & glucose
-Without blood/ oxygen/ glucose the heart cells cannot respire
119
What happens during coronary heart disease?
-Blockage of coronary artery by fat globules (plaques).
-Reduced O2 transport in blood leads to anaerobic respiration.
-Build-up of lactic acid creates an acidic environment, causing enzyme denaturation & increasing the risk of strokes.
120
What factors increase the risk of CHD?
-Poor diet
-Stress
-Smoking
121
How does poor diet increase the risk of CHD?
-Diets rich in saturated fats, salt, & alcohol increase cholesterol levels in the blood
-Leads to a higher risk of fatty deposits in arteries
122
How does stress increase the risk of CHD?
-Stress causes the release of hormones that increase blood pressure.
-Higher blood pressure raises the risk of fatty plaque buildup in arteries
123
How does smoking increase the risk of CHD?
-Nicotine in cigarettes causes vasoconstriction (narrowing of blood vessels).
-Increases the likelihood of fatty plaque formation in arteries
124
What are the key features of arteries & their function in the circulatory system?
-Transports oxygenated blood away from the heart (except the pulmonary artery).
-Thick muscular walls-> withstand high pressure.
-Narrow lumen-> maintain high pressure for blood circulation.
125
What are the key features of veins and their function in the circulatory system?
-Transports deoxygenated blood towards the heart (except the pulmonary vein).
-Thin walls-> allow skeletal muscles to exert pressure on veins.
-Wide-> lumen to transport large volumes of blood.
-Valves-> prevent backflow of blood under low pressure.
126
What are the key features of capillaries and their role in material exchange?
-Facilitates material exchange between cells (e.g., gas exchange).
-Thin walls (one cell thick) -> efficient material exchange via diffusion.
-Narrow lumen-> allows extensive branching, increasing surface area to volume ratio for efficient exchange.
127
Explain how the rate of transpiration is affected by changes in the environment
-High humidity decreases rate – because there is a lower water vapour concentration gradient;
-High temperature increases rate – as the water molecules have more kinetic energy and evaporate more rapidly;
-High wind speeds increase rate – as the water vapour outside the leaf is blown away, increasing the concentration gradient;
-High light intensity increases rate – as the stomata open more widely;
128
Explain two ways arteries are specialised to their role of carrying blood under high pressure
Thick muscular layer – contracts to maintain blood pressure;
Thick elastic layer – expands to prevent bursting / recoils to maintain blood pressure;
Narrow lumen – maintains blood pressure
129
Describe two differences between arteries & veins.
-Arteries have a thicker muscular layer;
-Arteries have a thicker elastic layer;
-Veins have a wider lumen;
-Only veins have valves;
