Revision 3 Flashcards
Give 1 example of a Barrier Method of Contraception.
3 marks
E.g. Condom, Female Condom or Diaphragm.
True or False? Barrier Methods of Contraception protect against Sexually Transmitted Infections (STI’s).
(3 marks)
True. Barrier Methods of Contraception do, but Hormonal Methods don’t.
The Combined Pill contains Oestrogen and Progesterone.
Explain how the Combined Pill reduces fertility.
(11 marks)
Taking Oestrogen every day means the levels of Oestrogen in the Blood are kept high. This inhibits the production of FSH and so stops an Egg from developing.
Progesterone reduces fertility by stimulating the production of thick Cervical Mucus which stops Sperm getting through the entrance to the Uterus and reaching an Egg.
Give 1 advantage and 1 disadvantage of Hormonal Contraceptive Methods.
(9 marks)
Advantage: e.g. when used correctly, Hormonal Methods are more effective at preventing pregnancy than Barrier Methods. With Hormonal Methods, the couple don’t stop and think about contraception each time they have intercourse.
Disadvantage: e.g. Hormonal Methods can have unpleasant side effects. And they don’t protect against STI’s.
Give 1 advantage of Hormonal Contraceptive Methods.
5 marks
E.g. when used correctly, Hormonal Methods are more effective at preventing pregnancy than Barrier Methods.
With Hormonal Methods, the couple don’t stop and think about contraception each time they have intercourse.
Give 1 disadvantage of Hormonal Contraceptive Methods.
2 marks
Hormonal Methods can have unpleasant side effects. And they don’t protect against STI’s.
Explain how Clomifene Therapy helps women who don’t Ovulate.
(5 marks)
Taking Clomifene causes more FSH and LH to be released by the Body, which stimulate Egg Maturation and Ovulation.
Meera is undergoing IVF Treatment. At which point in the IVF Process is Meera given the hormones FSH and LH?
Explain why Meera is given these hormones.
(5 marks)
FSH and LH are given to Meera before Egg collection. They are given to stimulate Egg Production so that more than 1 Egg can be collected.
True or False? Insulin causes Glucose to be released into the Blood.
(4 marks)
False. Insulin removes Glucose from the Blood.
Which Gland monitors and controls Blood Glucose concentration?
(1 mark)
The Pancreas
Explain why the body needs a constant internal environment.
7 marks
A constant internal environment is important because Cells need the right conditions in order to function properly (particularly for Enzyme Function). It can be dangerous for the body’s health if conditions vary too much from normal levels.
A person eats a Carbohydrate meal.
Their Blood Glucose levels raise after they have eaten.
How does their Blood Glucose levels reduce again?
(8 marks)
Insulin is secreted by the Pancreas. This causes Glucose levels to move from the Blood into the Cells of the Liver and Muscles, where it is stored as Glycogen.
Which Hormone increases the Blood Glucose levels?
5 marks
Glucagon acts to increase Glucose levels by converting Glycogen into Glucose, which is then released into the Blood.
Which Hormone lowers Blood Sugar levels?
1 mark
Insulin
How does Homeostasis affect Enzyme Action?
3 marks
Maintains optimal conditions (in the body), for Enzyme Action and all Cell Functions.
True or False? In Type 2 Diabetes, a person can become resistant to their own Insulin.
(3 marks)
True. The body cells no longer respond to Insulin.
Give 2 treatments for controlling Type 2 Diabetes.
3 marks
E.g. Eating a healthy diet, getting regular exercise, losing weight if needed.
What is Type 1 Diabetes? How is it treated?
9 marks
Type 1 Diabetes is where the Pancreas produces little to no Insulin. It is treated with Insulin therapy, where Insulin is injected into the Subcutaneous Tissue, from where it will enter the Bloodstream.
People with Type 1 Diabetes are also advised to exercise regularly and limit their intake of foods rich in Simple Carbs.
Calculate the BMI of someone who has a mass of 80kg and is 2m Tall.
BMI = Mass (kg) / (height (m))^2
(7 marks)
BMI = kg / m^2 BMI = 80 / 2^2 = 20
A woman has a waist and hip circumference of 100cm each.
Calculate her waist-to-hip ratio and explain whether she is at risk of Type 2 Diabetes.
(18 marks)
Waist-to-hip ratio = waist circumference (cm) / hip circumference (cm)
Waist-to-hip ratio = 100 / 100 = 1
This woman is at risk of Type 2 Diabetes. A ratio of above 0.85 for women is associated with an increased risk because it indicates that a lot of fat is being stored around the abdomen.
Which factors make Type 1 Diabetes different from Type 2: Type 1
(7 marks)
- Often diagnosed in childhood.
- Not associated with excess body weight
- Often associated with higher than normal ketone levels at diagnosis.
- Treated with insulin injections or insulin pump
- Cannot be controlled without taking insulin
Which factors make Type 2 Diabetes different from Type 1: Type 2
(7 marks)
- Usually diagnosed in over 30 year olds
- Often associated with excess body weight.
- Often associated with high blood pressure and/or cholesterol levels at diagnosis.
- Is usually treated initially without medication or with tablets.
- Sometimes possible to come off diabetes medication.
Give examples of differences between Type 1 and Type 2 Diabetes.
(7 marks)
Type 2: Usually diagnosed in over 30 year olds
Type 1: Often Diagnosed in childhood.
Type 2: Often associated with excess body weight, high blood pressure and/or cholesterol levels at diagnosis.
Type 1: Not associated with excess body weight but with higher than normal ketone levels at diagnosis.
List the differences between the treatment of Type 1 and Type 2 Diabetes.
(6 marks)
Type 1: Treated with insulin injections or insulin pump.
Type 2: Is usually treated initially without medication or with tablets.
Type 1: Cannot be controlled without taking insulin.
Type 2: Sometimes possible to come off diabetes medication.
What causes Type 1 Diabetes?
6 marks
Caused when the Pancreas fails to produce enough Insulin. This can be detected from an early age. It is characterised by uncontrolled High Blood Glucose Levels and it can be controlled by injecting Insulin.
What causes Type 2 Diabetes?
11 marks
Developed when the person’s body Cells no longer respond to Insulin produced by the Pancreas. It is more common in older people.
It can be controlled by a Carb controlled diet and an exercise regime. Carbs are digested into glucose, which raises the overall Blood Glucose level. There is a correlation between rising levels of obesity in the general population and increasing levels of T2D.
How does the size of an Organism affect its Surface Area to Volume ratio?
(3 marks)
The larger an Organism is, the smaller it’s Surface Area to Volume ratio.
Give 2 waist products that need to be removed from Cells.
2 marks
E.g. Carbon Dioxide and Urea.
Give 4 substances that Cells need to take in from the environment.
(4 marks)
E.g. Oxygen, water, dissolved food molecules and Mineral Ions.
Outline how Aerobic Respiration drives the need for the transport of gases in and out of Cells.
(4 marks)
Aerobic respiration requires Oxygen to be taken into Cells. Aerobic Respiration produces Carbon Dioxide that needs to be removed from the Cells.
Explain how Single-Celled Organisms can easily exchange substances with the environment, without the need for a transport system or an exchange surface.
(7 marks)
Single-Celled Organisms have a large Surface Area to Volume ratio. This means that enough gases and dissolved substances can diffuse directly into (or out of) the Cell to supply the needs of the Cell, so a transport system and an exchange surface are not needed.
A tiny elephant can be represented by a 3cm x 3cm x 3cm block.
Calculate the Surface Area to Volume ratio of the elephant.
(23 marks)
Surface Area = Length x Width of each side of the block = (3 x 3) x 6 = 54cm^2
Volume = Length x Width x Height = 3 x 3 x 3 = 27cm^3
So the Surface Area to Volume Ratio = 54 : 27 (can be Simplified to 2 : 1)
How can you calculate the Surface Area of an object?
4 marks
Surface Area = Length x Width of each side of the Object
How can you calculate the Volume of an Object?
6 marks
Volume = Length x Width x Height
How can you calculate the Surface Area to Volume ratio of something?
(17 marks)
Surface Area = Length x Width of each side (use cm^2 for blocks)
Volume = Length x Width x Height (use cm^3 for blocks)
Surface Area to Volume Ratio = SA : V
- Simplify when needed
What is the function of the Lungs?
4 marks
The Lungs transfer Oxygen to the Blood and remove waste Carbon Dioxide from it.
What are Alveoli?
4 marks
Alveoli are small air sacs in the Lungs where Gas Exchange takes place.
Explain why Alveoli need a good Blood Supply for efficient Gas Exchange.
(4 marks)
Alveoli need a good Blood Supply to maintain the Concentration Gradients of Oxygen and Carbon Dioxide.
Explain how Gas is exchanged between the Lungs and Blood that has just returned from the rest of the Body.
(13 marks)
The Alveoli are surrounded by Capillaries carrying Blood that has returned from the rest of the Body. The Blood contains lots of Carbon a Dioxide and not much Oxygen. In Alveoli, the Oxygen concentration is high and the Carbon Dioxide concentration is low. This means Oxygen diffuses out of the Alveoli into the Blood, and Carbon Dioxide diffuses out of the Blood into the Alveoli.
Some human groups that live at high altitude have larger Lungs than people who live at lower Altitudes.
Suggest how this could be an adaptation to high altitude, where there is less Oxygen available in the air.
(8 marks)
Having larger Lungs means that there is a larger Surface Area for Diffusion, so larger Lungs could be an adaption to help make sure that people who live at high altitude can get enough Oxygen into their Blood. This ensures that their Cells have enough Oxygen to maintain Aerobic Respiration.
Explain how the Adaptation of Alveoli’s (large) Surface Area allows for efficient Gas Exchange?
(14 marks)
Many alveoli are present in the Lungs with a shape that further increases surface area.
This allows for Gas Exchange to happen at a fast and more efficient rate. As more Oxygen (needed for Gas Exchange) can enter into the Alveoli, providing Oxygen to the Body’s Cells via diffusion. In the same way more Carbon Dioxide can diffuse out of the Cells into the Alveoli before being exhaled out.
Explain how the adaptation of the Alveoli’s thin walls are useful for Gas exchange.
(3 marks)
Alveolar walls are 1 cell thick providing gases with a short diffusion distance.
Explain how the adaptation of the Alveoli’s moist walls allow for efficient Gas Exchange.
(4 marks)
The Alveoli’s moist walls means gases dissolve in the moisture helping them to pass across the gas exchange surface.
Explain how the adaptation of permeable walls supports Gas Exchange in the Alveoli.
(2 marks)
Permeable walls allow gases to pass through easily.
Explain how the adaptation of an extensive blood supply supports Gas Exchange for the Alveoli.
(5 marks)
An extensive Blood supply ensures Oxygen Rich Blood is taken away from the Lungs and Carbon Dioxide rich blood is taken to the Lungs.
How is the large diffusion gradient adapted to help with gas exchange in the Alveoli?
(7 marks)
Breathing ensures that the Oxygen concentration in the Alveoli is higher than in the Capillaries so Oxygen moves from the Alveoli to the Blood. Carbon Dioxide diffuses in the opposite direction.
What adaptations are made to the Alveoli to make Gas Exchange more efficient?
(6 marks)
- Large Surface Area
- Thin, moist Permeable walls
- Good Blood supply
- Large Diffusion gradient
What other name can be used for Erythrocytes?
1 mark
Red Blood Cells
What is the function of White Blood Cells?
2 marks
WBC’s defend the body against infection.
What is Plasma?
2 marks
Plasma is the liquid that carries everything in Blood.
Describe the function of Lymphocytes.
6 marks
Lymphocytes are WBC’s that produce antibodies against Microorganisms. Some also produce antitoxins to neutralise any toxins produced by the Microorganisms.
Explain the importance of Haemoglobin in Red Blood Cells.
10 marks
Haemoglobin enables RBC’s to carry Oxygen through the body.
In the Lungs, Haemoglobin bonds to Oxygen to become Oxyhaemoglobin.
In Body Tissues, Oxyhaemoglobin splits up to release Oxygen to the Cells.
Besides the adaption of Haemoglobin in what other ways are Red Blood Cells adapted to their function?
(6 marks)
Red Blood Cells have a biconcave disc shape, which gives them a large Surface Area for absorbing Oxygen. They also have no Nucleus, which allows more room to carry Oxygen.
Some diseases can cause the number of Platelets in the Blood to fall to very low levels.
Why is it particularly dangerous if patients with these diseases start bleeding?
(5 marks)
Platelets help the Blood to clot at a wound, so patients with low numbers of platelets might not be able to stop bleeding because their Blood can’t clot properly.
What is another name for Platelets?
1 mark
Thrombocytes
What are the major types of blood cells in the human body?
6 marks
Red Blood Cells (erythrocytes)
White Blood Cells (leukocytes)
Platelets (thrombocytes)
How much of the Blood Tissue is taken up by Blood Cells (WBC’s, RBC’s and platelets)?
(7 marks)
A total 45% of the blood tissue by volume, is taken up by these 3 Blood Cells.
The remaining 55% of the volume composed of plasma, the liquid component of blood.
What is another name for White Blood Cells?
1 mark
Leukocytes
What is another name for Red Blood Cells?
1 mark
Erythrocytes
True or False? Arteries carry Blood to the Heart.
5 marks
False. Arteries carry the Blood away from the Heart. Veins carry Blood to the heart.
Which type of Blood Vessel has the largest Lumen?
1 mark
Veins
Which type of Vessel contains Valves? What is their function.
(3 marks)
Veins have Valves. They help to keep the Blood flowing in the right direction.
What is the advantage of the walls of Capillaries being only 1 Cell thick?
(6 marks)
It means the distance over which materials are exchanged is very small, so the rate of diffusion between Capillaries and Cells is high.
It takes 5 minutes for 1500ml of Blood to pass through an Artery.
Calculate the rate of Blood flow through the Artery in ml/min.
Use the equation: Rate of Blood flow = Volume of Blood / Time.
(6 marks)
Rate of Blood flow = Volume of Blood / Time
= 1500 / 5 = 300 ml/min.
Describe the difference in thickness between an Artery Wall and a Vein Wall.
Why does this difference exist?
(12 marks)
Arteries have thicker walls than veins. They carry Blood that has been pumped from the Heart at high pressure, so the walls have thicker layers of Muscle and Elastic Fibres to make them strong and elastic.
In Veins (which carry Blood back to the Heart), Blood is at a low pressure, so the walls don’t need to be as thick.
Capillaries branch out to form a network of Blood Vessels rather than continuing as a single Blood Vessel.
Suggest why.
(3 marks)
Capillaries branch out, allowing them to get close to every Cell in the body in order to exchange substances with them.
What are the main components of the Circulatory System?
3 marks
- Heart
- Blood
- Blood Vessels
What are the 2 main functions of the Circulatory System?
2 marks
- Transportation of substances
- Protection against disease
Explain the structure of the Red Blood Cell.
8 marks
Contain haemoglobin (rich in iron) to carry Oxygen. Biconcave shape to provide a large surface area for the diffusion of Oxygen. No Nucleus to provide more space for Haemoglobin.
Explain the structure of the White Blood Cell.
8 marks
Large cells that contain a nucleus. There are 2 types: Lymphocytes – make antibodies. Phagocytes – engulf and digest microorganisms.
What is the role of the Lymphocytes (type of WBC)?
Make antibodies.
What is the role of the Phagocytes (type of WBC)?
3 marks
Engulf and digest microorganisms.
Describe the structure of Platelets.
2 marks
Cell fragments (very small).
Describe Plasma.
2 marks
Straw coloured liquid.
What is the function of the Red Blood Cells?
1 mark
Carry Oxygen.
What is the function of the White Blood Cells?
2 marks
Defend the body against disease.
Describe the function of Platelets.
6 marks
Convert Fibrinogen to Fibrin. Fibrin forms a mesh that traps Blood. Important in Blood clotting and scab formation.
Describe the function of Plasma.
6 marks
Transports Blood Cells, digested food molecules (e.g. Glucose), Carbon Dioxide, Urea and Hormones.
Name the types of Blood Vessels.
3 marks
- Arteries
- Veins
- Capillaries
Describe the structure of Arteries.
9 marks
Thick walls with Muscle and Elastic Fibres to withstand high pressure. These features (of the walls) also allow the Artery to expand and recoil with each surge of Blood. The Lumen diameter is small and there are no Valves present in the Arteries.
Describe the Function of the Arteries.
4 marks
Carry Oxygenated Blood from the Heart to the rest of the body (Pulmonary Artery is the exception).
Describe the function of the Pulmonary Artery.
3 marks
Carries Deoxygenated Blood from the Heart to the Lungs.
Describe the structure of the Veins.
10 marks
The Lumen is large and reduces friction as the Blood moves through. Walls are thin and have very few Muscle and Elastic Fibres as Blood Pressure is low and does not surge through the Veins. Valves are present to prevent the backflow of blood.
Describe the function of the Veins.
4 marks
Carry Deoxygenated Blood from the body back to the Heart (the Pulmonary Vein is the exception).
What is the Function of the Pulmonary Vein?
3 marks
The Pulmonary Vein carries Oxygenated Blood from the Lungs to the Heart.
What is the function of the Capillaries?
8 marks
Allow the diffusion of substances (e.g. O2, CO2, dissolved food and Urea) between the Blood and the body’s Cells or vice versa.
Describe the structure of the Capillaries.
6 marks
Walls are 1 cell thick providing a thin, permeable surface for diffusion. They have a Small Lumen diameter. Blood moves through at a low pressure.
What is Lumen in the human body?
4 marks
Lumen (plural lumina) is the inside space of a tubular structure such as an Artery or a Vein.
Which side of the Heart pumps Deoxygenated Blood to the Lungs?
(1 mark)
Right side of the Heart.
Name the Blood Vessel which carries Blood into the Right Atrium of the Heart.
(1 mark)
Vena Cava
What is the Vena Cava?
5 marks
A large Vein that carries Blood to the Heart from other areas of the body. It is made up of 2 parts.
What are the 2 parts of the Vena Cava?
11 marks
Superior Vena Cava - carries Blood from the head, neck, arms, and chest.
Inferior Vena Cava - carries Blood from the legs, feet, and organs in the abdomen and pelvis.
What is the largest vein in the body?
1 mark
Vena Cava
What is meant by Cardiac Output?
3 marks
Cardiac output is the Total Volume of Blood pumped by a Ventricle every minute.
What is the function of the Valves in the Heart?
2 marks
Valves stop Blood from flowing backwards.
Describe the route that Blood from the Lungs takes through the Heart.
(7 marks)
Oxygenated Blood from the Lungs enters the Left Atrium through the Pulmonary Vein.
It then moves through to the Left Ventricle, and then leaves the Heart via the Aorta.
George is dissecting a sheep’s Heart.
What difference would allow him to differentiate the Right Ventricle from the Left Ventricle?
Explain the reason for this difference.
(8 marks)
E.g The thickness of the Ventricle Walls - the Left Ventricle will have thicker walls than the Right Ventricle. This is because the Left Ventricle has more Muscle so it can pump Blood around the whole body at high pressure, whereas the Right Ventricle only has to pump it to the Lungs.
A doctor tells Oskar that his heart rate is 60 beats per minute and his Cardiac Output is 4800cm^3 min^-1.
Calculate the Stroke Volume of Oskar’s Heart using the equation:
Cardiac Output = Heart Rate x Stroke Volume
(7 marks)
Stroke Volume = 4800 / 60 = 80cm^3
What type of Circulatory System do humans have? Explain your answer.
(5 marks)
Double Circulatory System;
- 1 circuit pumps Blood to the Lungs and back to the Heart.
- 1 pumps Blood around the rest of the Body.
In Respiration, is energy transferred to the environment or from the environment?
(3 marks)
To the environment (respiration is an Exothermic Reaction).
Where in the Body does Respiration take place?
2 marks
Respiration occurs in every cell in the body (it happens continuously).
Give the product(s) of Anaerobic Respiration in Plant Cells.
(2 marks)
Ethanol and Carbon Dioxide.
Despite having magical abilities. Egbert the polar bear still relies on Respiration to keep his body working.
Explain why Respiration is important for Polar Bears (even the magical ones).
(9 marks)
Respiration transfers (releases) energy for use in all living processes. Polar bears need energy for muscle contraction, keeping warm, and for metabolic processes (e.g. making larger molecules from smaller ones).
An athlete is doing some gentle warm-up stretches before a training session.
Give the word equation for the type of Respiration taking place in the athlete’s Muscle Cells.
(8 marks)
Glucose + Oxygen = Carbon Dioxide + Water (Aerobic Respiration is taking place).
At the end of an intense training session, an athlete feels pain in his muscles and he gets a cramp in one of his legs.
Explain why this has happened.
(8 marks)
The athlete has done vigorous exercise and his body hasn’t been able to supply enough Oxygen to his Muscles for Aerobic Respiration, so his Muscles has been respiring Anaerobically as well.
Anaerobic Respiration produces Lactic Acid, which has built up in the athlete’s Muscles and caused the pain and the cramp.
What type of Respiration uses Oxygen?
1 mark
Aerobic Respiration
What Respiration does not require Oxygen and produces Lactic Acid (commonly found in Muscles after exercise)?
(1 mark)
Anaerobic Respiration
What are the products of Aerobic Respiration?
4 marks
Carbon Dioxide + Water
The products do not contain stored chemical energy.
What are the products of Anaerobic Respiration?
3 marks
Lactic acid or ethanol + ATP molecules.
How and where does Anaerobic respiration take place?
8 marks
In the absence of Oxygen and is seen in lower animals, in the Cytoplasm of Cells.
Some organisms and tissues can continue to respire if the oxygen runs out via Anaerobic Respiration.Human muscle can respire anaerobically for short periods of time.
What is the Aerobic Respiration Chemical Equation?
7 marks
C6H12O6 + 6O2 → 6CO2 + 6H2O + energy released
What is the Aerobic Respiration Word Equation?
5 marks
Glucose + oxygen → carbon dioxide + water + energy released
Where does Aerobic Respiration occur in the Body’s Cells?
4 marks
The first stages of Respiration occur in the Cytoplasm of Cells, but most of the energy released is in the Mitochondria.
Describe the process of Aerobic Respration.
7 marks
Aerobic Respiration is the process of respiration in which Oxygen is used to break down Food Molecules. Glucose is the molecule normally used for Respiration – it is the main Respiratory Substrate. Glucose is oxidised to release its energy.
Why do all Organisms Respire?
7 marks
All organisms respire in order to release energy to fuel their living processes. The Respiration can be Aerobic, which uses Glucose and Oxygen, or Anaerobic which uses only Glucose.
What is the Word Equation for the process in which Glucose in Yeast Cells is converted to Carbon Dioxide and Ethanol (Anaerobic Respiration of the Yeast Cells)?
(6 marks)
Glucose → ethanol (alcohol) + carbon dioxide + energy
What is the Word Equation for Anaerobic Respiration?
4 marks
Glucose → lactic acid + energy
Describe the process of Anaerobic Respiration in the Human Muscles.
(5 marks)
Human muscle can respire Anaerobically for short periods of time – even though the process is relatively inefficient, it’s better to continue respiring and be able to run away from danger.
How much energy is released during Aerobic Respiration?
1 mark
Relatively large amount.
How much energy is produced during Anaerobic Respiration?
2 marks
Small amount, but it occurs quickly.
What are the products of Anaerobic Respiration in Mammalian Muscles compared to Yeast and Plants?
(10 marks)
Mammalian muscle: Lactic acid.
Yeast: Ethanol (alcohol) and Carbon Dioxide.
Some plants: Ethanol and Carbon Dioxide. The products still contain stored chemical energy.
What is the product of Anaerobic Respiration in a Mammalian Muscle?
(1 mark)
Build up of Lactic Acid
What are the products of Anaerobic Respiration in Yeast (Fungi)?
(4 marks)
Ethanol and Carbon Dioxide.
It’s preferable to release less energy but remain alive.
What are the products of Anaerobic Respiration in some Plants?
(4 marks)
Ethanol and Carbon Dioxide. The products still contain stored chemical energy.
Explain the Oxidation of Glucose in Anaerobic Respiration.
3 marks
Incomplete. The products of respiration still contain energy.
Describe the Oxidation of Glucose in Aerobic Respiration.
1 mark
Complete
How much Oxygen is required for Anaerobic Respiration
4 marks
None. Mammalian Muscles often use Anaerobic Respiration in the absence of Oxygen or when in short supply.
When does Anaerobic Respiration take place in human Muscles?
1 mark
During strenuous exercise.
What is the alcohol (Ethanol) produced during Anaerobic Respiration in the Yeast Cells used for?
(2 marks)
It is the basis of wine and beer production
Give 1 factor that could affect the rate of Respiration in an Organism.
(1 mark)
Temperature
Why would you put soda lime in a respirometer?
2 marks
Soda lime would absorb any CO2 produced so that it won’t affect the results.
Andrea is performing an experiment to investigate respiration in germinating peas. She uses a test tube of boiled peas.
Why would Andrea include a test tube with boiled peas in the experiment?
(6 marks)
These peas are dead and can’t respire, so the tube with the boiled peas acts as a control. It allows Andrea to be sure that any changes that happens in the tube with the live peas is caused only by the peas respiring.
By the end of Andreas experiment (investigating respiration in germinating peas), the coloured liquid in the manometer moves towards the test tube containing the live peas.
Explain why.
(7 marks)
The peas use up Oxygen in the tube as they respire, leading to a decrease in the Volume of the air in the test tube. The decrease in Volume reduces the pressure in the tube, causing the coloured liquid in the manometer to move towards the test tube containing the peas.
How can Andrea measure the rate of Respiration in the live peas (when performing an experiment to investigate respiration in germinating peas)?
(6 marks)
Andrea can measure the distance moved by the liquid in a given time. This value can then be used to calculate the Volume of Oxygen taken in by the peas per minute. This will give the Rate of Respiration
What do Respirometers measure?
2 marks
Respirometers tell us, how much Oxygen is being used up by Respiration.
What equipment is needed when Investigating Respiration in Germinating Peas?
(8 marks)
Water bath, soda lime, live peas, boiled peas, manometer, calibrated scale, syringe and closed tap.
What is an ecosystem?
3 marks
A community of organisms along with all the non-living (abiotic) conditions.
What is meant by the term ‘interdependence’?
4 marks
The way that each species in a community depends on other species for things such as food, shelter, etc.
Which of the following are Biotic factors?
- new predators
- Temperature
- Light intensity
- moisture levels
- food availability
(2 marks)
New predators and food availability.
Surface-are-to-volume Ratio
4 marks
Amount of Surface Area per unit Volume of an object or collection of objects.
What is the difference between a population and a community.
(6 marks)
A population includes all the organisms of 1 species in a habitat, whereas a community includes all the organisms of different species in a habitat.
A pine plantation contains large pine trees that have been planted to produce a large amount of wood. To maximise the amount of wood produced, the trees have been planted very close together. Very few plants grow below these trees.
Suggest why.
(11 marks)
- Light Intensity at the forest floor is likely to be very low because the sunlight is being blocked out by the densely packed pine trees. Without enough light, plants can’t Photosynthesise, so they are unlikely to grow on the forest floor.
- Plants will also have to compete with the trees for Nutrients and Water in the soil. With a high number of pine trees absorbing them, there might not be enough to allow the growth of other plants.
What can changes in Abiotic and Biotic factors do?
5 marks
Directly affect the population size of a Species. This can have knock-on effects on other Species due to Interdependence in the Ecosystem.
What is a Quadrat?
2 marks
A Quadrat is a square frame enclosing a known area.
Lucas wants to study the clover population in his school field using Quadrats.
Suggest 1 way that he could ensure he places the Quadrats randomly.
(5 marks)
E.g. he could divide a map of the field into a grid, and use a random number generator to select coordinates at which to place the Quadrat.
Sea sandwort is a plant found at beaches. Stacey wants to investigate how the distribution of sea sandwort changes with distance from the sea.
Suggest a method she could use for this.
(10 marks)
- Stacey could form a belt transect on a beach by marking out a line at a right angle to the sea.
- She could then place Quadrats along the transect, either next to each other or at regular intervals.
- In each Quadrat she could record the number of sea sandwort plants or the percentage cover.
Alejandra counted the number of buttercups in 6 Quadrats in her garden.
Her results were: 3, 2, 1, 4, 5, 3
Calculate the mean number of buttercups per Quadrat.
(6 marks)
Mean = 3 + 2 + 1 + 4 + 5 + 3 = 18 / 6 = 3
Ans: 3 buttercups per Quadrat.
Victor used a Quadrat with an area of 0.5m^2 to investigate the number of daisies in a 1000m^2 field. He found a mean of 3 daisies per Quadrat.
Estimate the total number of daisies in the whole field.
(10 marks)
There’s a mean of 3 daisies per 0.5m^2, so there’s a mean of 3 x 2 = 6 daisies per 1m^2 .
Total number of daisies in a field =
Mean per m^2 x Total Area = 6 x 1000 = 6000 daisies.
Belt transects aren’t just used to find out how organisms are distributed.
What are their other uses?
(3 marks)
Measure things, such as height of plants, to see if they change along a Gradient.
What is Biodiversity?
2 marks
Biodiversity is the variety of living organisms in an Ecosystem.
What is a Non-indigenous Species?
4 marks
A Non-indigenous Species is one that doesn’t naturally occur in an area. (They may have been introduced intentionally or unintentionally by people).
How can eutrophication cause the plants at the bottom of a lake to die?
(7 marks)
Eutrophication is an excess of Nutrients in the water. It can cause Algae in the lake to grow fast and block out the light. Plants at the bottom of the lake won’t be able to Photosynthesise due to lack of light, so they’ll start to die.
Apart from Eutrophication, how could the Biodiversity of a lake be reduced if someone starts to farm fish in large nets within the lake?
(10 marks)
Fish farms can host large numbers of Parasites, which could get out of the farm and infect wild animals in the lake and potentially kill them. Predators could be attracted to the nets and become trapped in them and die. Sometimes farmed fish can escape into the wild, which can cause problems for wild populations of Indigenous Species.
The White-clawed Crayfish Species is Native to Britain. The arrival of the American Signal Crayfish into British waters has contributed to a decline in the number of white-clawed crayfish as they carry a pathogen that causes ‘crayfish plague’ in the native species.
Explain how else the arrival of the signal crayfish might have affected the population size of the white-clawed crayfish.
(6 marks)
The American Signal Crayfish might be out-competing the White-clawed Crayfish for resources such as food and shelter, causing the White-clawed Crayfish population to decline.
What is a benefit of having fertilisers and fish farms?
1 mark
Important for making sure we have enough food.
What we need to do with fertilisers and fish farms for Biodiversity?
(2 marks)
Take steps to reduce their impact on Biodiversity.
True or False? Conserving one Species can prevent the Extinction of other species.
(7 marks)
True. The Extinction of 1 species will affect the whole food chain (e.g. species that used to feed on the now extinct species).
Conserving 1 species may therefore help others to survive.
What is the advantage of planting multiple tree species during reforestation, rather than planting a single tree species?
(6 marks)
Replanting with multiple species will result in higher Biodiversity that with a single tree species. More tree species will then provide food resources and habitats for more animals.
What is reforestation?
3 marks
When land where a forest previously stood is replanted to form a new forest.
Describe one way that conservation programmes can protect the human food supply.
(6 marks)
Conservation programmes can prevent over-fishing from reducing the fish stocks in the world’s oceans. This would ensure that future generations will have fish to eat.
What is ecotourism? What are it’s benefits?
6 marks
Ecotourism is environmentally-friendly tourism. It helps to bring money into Biodiverse areas, helping to fund conservation work that is taking place there. Ecotourism also provides employment opportunities for locals.
Outline the conservation methods that could be used to prevent the Extinction of rare tree species that is threatened by deforestation.
(9 marks)
The tree species’ natural habitat could be protected from Deforestation or restored by a Reforestation programme. Trees could be grown in safe areas outside of their natural habitat to increase numbers. Seed banks could also be used to store and distribute the seeds of the tree.
What is ecosystem diversity?
2 marks
Ecosystem diversity is the number of distinct ecosystems in a defined area.
What are the 2 factors of Species Diversity?
4 marks
The number of different species in an ecosystem and the proportion of each species in the ecosystem.
What does Genetic diversity relate to?
5 marks
Genetic diversity relates to genetic variation of the number and frequency of alleles of a specific gene.
What are the three measurable components of biodiversity?
3 marks
- Genetic diversity
- Species diversity
- Ecosystem diversity
What threatens Biodiversity?
5 marks
- Overexploitation (e.g. over-fishing/over-harvesting)
- Habitat fragmentation
- Introduced species
Explain the Bottleneck Effect.
7 marks
The Bottleneck Effect is when a population has been almost wiped out possibly by a natural disaster. When the surviving population is small lots of Genetic info is lost, which can prevent the population adapting to future environmental changes.
What happens when a Species is very nearly wiped out?
4 marks
Genetic information is lost preventing the (surviving) population adapting to future changes in the environment.
Give examples of Overexploitation.
2 marks
- Over-fishing
- Over-harvesting
What is the benefit of the early intervention of Overexploitation?
(3 marks)
The population might be able to recover if exploitation is stopped sooner rather than later.
What is the possible outcome of Overexploitation?
6 marks
Species (populations) risk extinction.
However, some species have naturally low genetic diversity in their population but yet remain a viable species.
Explain Habitat Fragmentation.
5 marks
Habitat fragmentation is when a habitat is broken up into smaller fragments, or sections. Over time, the edges of the fragments are degraded and the fragments decrease in size further.
What risks come with Habitat Fragmentation?
8 marks
- Habitat loss of some species.
- Increased competition between species as the fragment becomes smaller; decreasing Biodiversity.
- Each smaller fragment can only support a smaller biodiversity compared to the original habitat.
What is a benefit of Habitat Fragmentation?
7 marks
Habitat fragments can be linked by habitat corridors which allow the movement of animals between fragments.This helps to increase species diversity as species can mate, find food after local extinctions.
What is the meaning of Introduced Species?
7 marks
Introduced species are those that have been moved intentionally or unintentionally by humans into a new geographic location where they are not naturally found.
Some may become established in this new location and are then termed naturalised species.
What are Invasive Species’?
11 marks
When Naturalised Species spread rapidly and outcompete/prey on Native Species. They can eliminate native species therefore reducing species diversity.
- They may spread rapidly because this new location is free of predators, parasites and competitors that would normally limit their population in their natural environment.
What is Extinction?
4 marks
Extinction is when a group of organisms fail to adapt to the environment and therefore cannot survive. This is a natural process.
How many mass extinction events have Fossils shown?
1 mark
7
After Extinctions what has happened to remaining organisms?
(3 marks)
Biodiversity has slowly increased as the remaining organisms have adapted to the new environment.
How can the rate of extinction be calculated?
8 marks
From the presence or absence of higher animals and birds. Normal extinction rates for these animals are compared with current extinction rates.
This is only an estimate and can be used to calculate the presence of little-known organisms.
What is contributing to the Extinction rate? Give an example.
(5 marks)
The spread and increase of the human population.
E.g. the Extinction of the Mega Fauna (Woolly Mammoth) coincided with the spread of humans.
Give an example of an action committed by humans that is causing the current rate of Species extinction to climb.
(3 marks)
The destruction of natural habitats by humans is causing the current rate of species extinction to be much higher than the natural background rate.
There is increasing evidence that the level of Carbon Dioxide in the Earth’s atmosphere is rising.
What is responsible for this rise?
(1 mark)
There is evidence that humans are responsible for the rise in CO2 levels.
Give 2 reasons why there is more Carbon Dioxide in the Earth’s atmosphere.
(6 marks)
- Increased combustion of Fossil Fuels has released more CO2.
- Increased Deforestation has reduced the amount of CO2 being removed from the atmosphere by photosynthesis.
What is the Greenhouse Effect?
10 marks
Greenhouse gases (like CO2) form a blanket around the Earth’s atmosphere. This ‘greenhouse blanket’ allows heat from the Sun to enter the atmosphere but then traps it - causing the Earth’s temperature to increase and is known as global warming.
What is causing Global Warming?
2 marks
An increase in atmospheric Carbon Dioxide is to blame for global warming.
How can humans reduce the effects of global warming?
8 marks
- Planting more trees and reducing deforestation to absorb more CO2 from the atmosphere.
- Burning fewer Fossil Fuels by using alternative fuels to reduce the amount of CO2 entering the atmosphere.
- Being more energy efficient to reduce the amount of CO2 entering the atmosphere.
What effects is global warming having on the earth?
7 marks
- Melting polar ice caps
- Rising sea levels
- Flooding
- Climate change - storms and drought
- Loss of habitats
What can have a negative effect on Biodiversity?
3 marks
- Deforestation
- Burning Fossil Fuels
- Using excess Fertiliser
If the current level of deforestation continues, rainforest resources will be completely destroyed in the next few decades.
In order to address this problem, what have some countries developed?
(1 mark)
Sustainable woodlands
Within Sustainable Woodlands, timber can still be harvested in a controlled way.
What strategies have been adopted for this reason?
(8 marks)
- Only a small number of large trees are harvested at the one time.
- Saplings are planted to replace the trees harvested (reforestation).
- Harvesting of the same area does not happen again until the medium trees have grown to become large (after a period of 25–30 years).
What are International Treaties?
7 marks
International treaties are ways in which humans are trying to reduce global CO2 levels by agreeing to international strategies.
They are legally binding and in 2015, 195 countries signed up to bring about positive change in this field.
An example of an International Treaty is The Paris Agreement.
Explain this agreement.
(8 marks)
The Paris Agreement is a legally binding international treaty on climate change. It was adopted by 196 Parties at COP 21 in Paris, in 2015 and entered into force in 2016.
What is Timber?
1 mark
Wood used in building and making furniture.
What are Alternative Fuels?
2 marks
A fuel that is not a fossil fuel.
What is a Sapling?
1 mark
A young tree.
How is Carbon transferred between organisms in an Ecosystem?
6 marks
Compounds containing Carbon are passed up the food chain when animals eat plants and other animals, and when microorganisms break down dead organisms.
Describe the role of Respiration in the Carbon Cycle.
3 marks
When organisms respire, Carbon is returned to the atmosphere as Carbon Dioxide.
Give one process in the Carbon Cycle involving plants that is missing from the list:
Carbon compounds in plants => Photosynthesis, CO2 in the air, Plant respiration, products made from plants
(1 mark)
Animals feeding on plants
Burning Fossil Fuels is contributing to a rise in the amount of Carbon Dioxide in the atmosphere, which is causing Global Warming.
Suggest why planting trees is recommended as a way of slowing down Global Warming.
(5 marks)
Trees remove Carbon Dioxide from the air during Photosynthesis. Planting trees will therefore help counteract the increase in CO2, helping to slow Global Warming.
Explain how microorganisms are involved in cycling materials through an Ecosystem.
(9 marks)
Microorganisms (such as bacteria/fungi) break down dead organisms and the waste products of living organisms, returning elements to the soil or air. Microorganisms also respire, which returns CO2 to the atmosphere.
Why is it important that Carbon is being constantly recycled in an Ecosystem?
(6 marks)
There’s only a fixed amount of Carbon in the world, so it must be constantly recycled for there to be enough Carbon available to the organisms in an Ecosystem. This is vital because Carbon is an element in materials that living things are made from.
What is an un-natural process in the Carbon Cycle.
3 marks
Burning things like Wood and Fossil Fuels (also releases Carbon into the atmosphere).
Rain, snow, sleet, or hail that falls to or condenses on the ground. Creating water in the atmosphere.
What is the name of this water?
(1 mark)
Precipitation
What term is used for the process of removing salt from sea water?
(1 mark)
Desalination
What is Potable water?
2 marks
Potable Water is water that is suitable for drinking.
Describe how water from the land, sea and plants form clouds.
(10 marks)
Energy from the Sun makes Water evaporate from the land and sea, turning it into water vapour. Water also evaporates from plants (transpiration). Warm air rises, so the warm water vapour is carried upwards, where it condenses to form clouds.
What is the process called in which water evaporates from plants?
(1 mark)
Transpiration
Why is it sometimes necessary in some areas to remove salt from sea water to produce drinking water?
(6 marks)
During a drought, there might not be enough precipitation in an area to provide enough fresh water for drinking. In these cases, it may be necessary to produce Potable water from sea water through Desalination.
Explain how reverse Osmosis can remove salt from salty water.
(11 marks)
- Salt water is first treated to remove solids, before being fed at a very high pressure into a Vessel containing a Partially Permeable Membrane.
- The pressure causes the water molecules to move from a higher salt concentration to a lower salt concentration (the opposite direction to Osmosis).
- As the water is forced through the membrane, the salts are left behind, removing them from the water.
Components of the Water Cycle
12 marks
Percolation (Collection) and Surface run-off ——> Evaporation (Ocean)/ Transpiration (land/ trees) ——> Water Vapour —-> Condensation —> Cooling (Clouds) —-> Precipitation
Evaporation
Name 4 Forms of Condensation.
4 marks
Dew, Fog, Frost, Mist
Explain Evaporation.
7 marks
Energy from the Sun heats the Earth’s surface and water evaporates from oceans, rivers and lakes. The warm air rises, carrying water vapour with it.
Explain Transpiration.
2 marks
Transpiration from plants releases water vapour into the air.
Explain Condensation.
5 marks
The moist air cools down as it rises. Water vapour condenses back into liquid water, and this condensation process produces clouds.
Explain Precipitation.
8 marks
As the water droplets in the cloud get bigger and heavier, they begin to fall as rain, snow and sleet. This is called precipitation (it is not the same as precipitation in Chemistry).
What is Nitrogen Fixation?
7 marks
Nitrogen Fixation is the process of turning Nitrogen Gas (N2) from the air into Nitrogen-Containing Ions in the soil which plants can use.
What type of Bacteria turn Ammonia into Nitrates?
4 marks
Nitrifying Bacteria (They turn Ammonia into Nitrites and then into Nitrates).
Denitrifying Bacteria thrive in waterlogged, poorly drained soils.
Suggest why a farmer might want to ensure that his fields are well drained.
(11 marks)
Denitrifying Bacteria turn Nitrates back into N2 Gas. This means that there is less Nitrogen in the soil that plants can use. A farmer might therefore want to ensure his fields are well drained so that Denitrifying Bacteria don’t grow so well. This would mean that the soil is more likely to have enough Nitrogen to allow the farmer’s crops to grow well and the farmer might not need to use as much fertiliser.
Farmer Siobhan grows maize plants every other year, and grows broad beans in the years in between. Broad beans are a Nitrogen-fixing crop.
Suggest why Siobhan doesn’t grow Maize plants every year, despite them making more money than Broad Beans.
(10 marks)
If Siobhan grows Maize every year, the Nitrogen content of the soil will decrease over time and the Maize won’t be able to grow very well after a few years. Growing Broad Beans will increase the amount of Nitrates in the soil because Broad Beans are a Nitrogen-Fixing Crop. This means that there will be more Nitrates available to the Maize when it is grown in the next year.
Suggest a method that could allow Siobhan to grow Maize crops every year.
(3 marks)
Siobhan could add Fertiliser to her fields to replace the Nitrogen that is lost from the soil during each year’s harvest.
What is the Sl base unit for mass?
1 mark
Kilograms
Are findings in peer-reviewed scientific articles always correct?
(5 marks)
No. The peer-review process helps to detect false claims and find obvious errors but it doesn’t necessarily mean that findings are correct.
What does it mean if scientific results are said to be reproducible?
(4 marks)
If the experiment is carried out by another person, a different method is used or a different piece of equipment is used, the results will still be similar.
Fiona notices that a Species of a Plant in a park grew taller in the shade of a tree than it did out in the sun.
Suggest a hypothesis that could explain Fiona’s observation.
(2 marks)
Plants of that species grow taller in lower light levels.
The likelihood of having an accident while in a car is greater than having an accident while skydiving, but more people are willing to go in a car than go skydiving.
Suggest one reason for this.
(6 marks)
Although the risk of an accident while skydiving are lower, the consequences of an accident are likely to be more severe so fewer people are willing to accept that risk.
Driving is a more familiar activity than skydiving so people’s perception of the risk is likely to be inaccurate.
Give 2 reasons why data based on larger sample sizes is better than data based on smaller sample sizes.
(4 marks)
- A larger sample will more accurately represent the whole population.
- It’s also easier to spot anomalies if the sample size is larger.
What type of error is caused by reading data from the top of the meniscus rather than the bottom when measuring volumes of liquids in a measuring cylinder?
(1 mark)
A systematic error.
Shivani counts the number of ladybirds of different species in an area of woodland.
Suggest how Shivani could graphically present her data.
(4 marks)
A Bar chart.
The data is categoric - each species of ladybird is a distinct category.
A graph shows the volume of water lost by a plant via transpiration plotted against time.
Calculate the rate of transpiration in cm^3 / minute when the time goes up in 2’s and the water loss is presented in numerical order. X = 10 Y = 4
(10 marks)
Pick 2 points on the graph that are easy to read - X = 10, Y = 4
Rate of transpiration =
gradient = change in Y / change in X
= 4 / 10
= 0.4 cm^3 / minute
Ans: 0.4 cm^3 / minute
A scientist carried out an experiment that measured someone’s heart rate in beats per minute (bpm). During 3 repeats, the scientist measured the Heart rate as 80bpm, 77bpm and 83bpm.
Calculate the mean and uncertainty of the data.
(17 marks)
Mean = total of number of beats / number of repeats
= (80 + 77 + 83) / 3
= 240 / 3
= 80bpm
Uncertainty = range / 2
= (83 - 77) / 2
= 6 / 2
= + (-underlined/plus over minus) 3bpm
Why do you need to wear a lab coat when using chemicals in an experiment?
(3 marks)
To protect your skin and clothing in case there’s a spillage.
If you capture organisms for an investigation, where should you release them?
(2 marks)
In the original habitat where you captured them.
Darrel is investigating Osmosis using potato pieces placed in different concentrations of sucrose solution. He cuts equally sized cylinders from a potato and divides the cylinders into groups of 3.
Describe how he can find the initial mass of each group.
(6 marks)
Darrel should start by putting a container on a balance and setting the balance to zero. Then he can place 3 potato cylinders into the container and record their mass. He can repeat this for each group of potato cylinders.
Darrel puts different concentrations of Sucrose Solution into different beakers. He uses a measuring cylinder to ensure each beaker contains the same volume.
Describe how he should read the volume when measuring the sucrose solution.
(5 marks)
Darrel should read the volume from the bottom of the meniscus (the curved upper surface of the liquid) when it’s at eye level.
When working with a Bunsen Burner, what safety precautions should you take?
(14 marks)
- When using a Bunsen Burner you should wear safety goggles to protect your eyes.
- You should put the Bunsen Burner on a heatproof mat.
- If your Bunsen Burner is lit but you’re not using it, you should close the hole so that the flame becomes yellow and visible.
- You should use Tongs or a Tripod and Gauze to hold things over the flame.
- If you’re heating a Vessel, make sure the opening is pointed away from yourself and others.
Name a piece of apparatus that can be used to heat a solution.
(3 marks)
A solution can be heated using a Bunsen Burner, Water Bath or Electrical Heater.
True or False? Water baths are used to maintain the pH of a solution.
(4 marks)
False. They are used to heat and maintain substances at a specific temperature.
Describe the steps you should taken when using a thermometer to correctly measure the temperature of a solution.
(5 marks)
Completely submerge the bulb of the thermometer in the solution and wait for the temperature to stabilise before taking a reading. Read off the thermometer scale at eye level.
Loretta is measuring the volume of gas produced by pondweed by counting the number of bubbles produced in 1 minute.
Explain why this method could be inaccurate.
(4 marks)
Counting bubbles could give an inaccurate result because the bubbles could be different sizes and Loretta might miss some if they’re produced quickly.
Asdren is doing an experiment to find out the Optimum pH of an enzyme. First he wants to determine whether it works best in Alkaline or Acidic Conditons.
Suggest how he could check whether his solutions are Acidic or Alkaline.
(8 marks)
He could test the solutions with red and blue Litmus paper. (If the solution is acidic Blue Litmus paper will turn Red, and if the solution is Alkaline Red Litmus paper will turn Blue.)
Asdren discovers that the Enzyme works best in Acidic Conditions. He sets up a range of different Acidic Solutions to try and determine the exact pH at which the Enzyme works best.
Suggest 2 ways that he could measure the pH of each of these solutions.
(7 marks)
- He could add a couple of drops of Universal Indicator to each solution. He could then use the colour of the solution to estimate its pH.
- He could also use a pH meter to give an accurate value for the pH of each solution.
Explain the process in which an electrical impulse crosses a synapse.
(18 marks)
It cannot directly be done.
- An electrical nerve impulse travels along the axon of the first neuron (Presynaptic Neuron).
- When the nerve impulse reaches the Dendrites at the end of the Axon, chemical messengers called Neurotransmitters are released.
- These chemicals diffuse across the Synaptic Cleft.
The chemicals bind with Receptor Molecules on the membrane of the second neuron (Postsynaptic Neuron). - The Receptor Molecules on the second neuron can only bind to the specific Neurotransmitters released from the first neuron.
- This process (binding to receptors) stimulates the second neuron to transmit an electrical impulse along its Axon. The signal therefore has been carried from one neuron to the next.
Describe and Explain two reasons why the grass in field B would grow more than the grass in field A. - part 1;
The Production of ATP, Oxygen and it’s benefits for Plant growth
(2 marks)
Field B will grow more than Field A due its high percentage of Oxygen (air) found in the soil. 39% making it the highest O2 to soil ratio with a greater aerobic intensity. O2 makes the process of respiration, both Aerobic and Cellular more efficient in a plant. Grass will use the energy from sunlight combined with Carbon Dioxide + Water to produce O2 and sugar (glucose) . O2 allows for cellular respiration which converts the Glucose produced in Photosynthesis into ATP, a source of energy for Biological processes. This energy can then be used for life processes supporting in the growth of the grass and clover.
Describe and Explain two reasons why the grass in field B would grow more than the grass in field A. - part 2;
Plant Cell Respiration, Photosynthesis, Nitrogen Fixing Bacteria, Aerobic Composting, Nitrate Nutrition and Denitrification
(3 marks)
- Although the Plant cells generally generate their own O2 via Photosynthesis, they also respire. Their leaves need to capture energy from the sun for this to be possible which can present a problem when there is little sun. During these times when there is little - to no access to sunlight, plants will take in more O2 than they produce during Photosynthesis.
- This process happens throughout the Organism (seeds, roots, leaf) including in parts of the plant that don’t photosynthesise. Roots can drown in waterlogged soil without access to O2. Growing plants will release more O2 than consumed allowing other organisms to breathe.
- Field B grows clover plants which contain Nitrogen Fixing Bacteria; bacterium that convert Nitrogen Gas (N2 - Free Nitrogen) from the atmosphere into ammonia, which can be converted into Ammonium compounds.
- Bacteria/fungi using O2, break down protein found in dead plants/animals, urine and faeces into ammonia through Aerobic composting. Ammonium is converted into Nitrates with help from Nitrifying Bacteria, a Process quickened by the presence of O2 and higher temperatures. Plants and Fungi use both Nitrates as a source of nutrition. To ensure sufficient nodule formation and optimum growth of legumes including Clovers. An organism found in Field B.
- Less Denitrification, changing Nitrates into gas, will happen in this soil as a result of Nitrogen Fixing Bacteria. This process brings with it disadvantages and is not healthy for the soil and plants. Denitrifying Bacteria does not require Oxygen and thrives in waterlogged soil, meaning with less waterlogged soil the harder it is for DB to carry out their job.
Describe and Explain two reasons why the grass in field B would grow more than the grass in field A.
Nitrogen Gas, the absorption of Nitrogen, Root Hair Cells and Absorption of Minerals via Active Transport/Uptake
(6 marks)
- Nitrogen Gas contains amino acids and proteins, essential for the growth and repair of plant and animal cells. These can be made in the grass in Field B, which can be passed on to primary producers during consumption.
- Although they cannot absorb it directly, plants can absorb Nitrogen in the form of Nitrates which are taken into the plant through the Specially Adapted Root Cells, Root Hair Cells. Which have a long extension with a large surface area for absorption.
- Nitrates and Minerals are absorbed by Active Uptake/Transport in which the mineral moves against a concentration gradient, from an area of low concentration to an area of high concentration in the soil. This takes place in the Plant Root. Aerobic respiration creates the energy needed to move against the concentration gradient with the support of O2.
