Everything needed for 4th Year Exam Flashcards
Complete the Acronym for MRS H GREN
Movement
Respiration
Sensitivity
Homeostasis
Growth
Reproduction
Excretion
Nutrition
Describe common features of plant cells
Cells contain chloroplasts and can carry out photosynthesis. Cell wall is cellulose, store carbohydrates via starch or sucrose. Examples include peas, beans or maize.
Describe common features of animal cells
They cannot photosynthesise, they have no cell walls, can store carbohydrates as glycogen. Examples of animals include mammals and insects.
Describe common features of a fungi (Not cell structure)
Cannot photosynthesize, Body organised into mycelium and made up of thread-like structures called Hyphae. Cell walls made of chitin, they have a saprophytic nutrition, store carbs as glycogen. Examples include Mucor and Yeast
Describe common features of Protoctista (Not cell structure)
Single-celled organisms, Some like Amoeba have features of an animal cell but some like Chlorella have chloroplasts and are more like plants. A pathogenic example is Plasmodium.
Describe common features of bacteria. Remember these are prokaryotes not eukaryotes.
Single-celled organisms. Have cell wall, cell membrane cytoplasm and plasmids and a singular chromosome of DNA. Mixture of autotrophs, saprophytes and feeding off living organisms.
Define pathogen
Any microorganism that can cause illness.
What kingdoms to pathogens include
Fungi, bacteria, Protoctista (and viruses)
Describe common features of a virus.
They are not living organisms and are incredibly small particles. There is no cellular structure but have a protein coat and contain either DNA or RNA.
They are all parasites and can only reproduce inside other organisms. Examples include the flu, HIV or Coronavirus
Cell structure of a fungi cell
Cell membrane, cytoplasm, mitochondria, nucleus, ribosomes and a cell wall made of chitin.
Function of the nucleus
Contains the cell’s DNA and controls activity within the cell.
Function of the cytoplasm
A jelly-like substance that is the site of chemical reactions.
Function of the cell membrane
Controls what goes in and out of the cell
Function of the cell wall
Allows the cell to hold its shape and supports the cell and the plant.
Function of mitochondria
The site of respiration
Function of chloroplasts
The site of photosynthesis. Contains chlorophyll (a green pigment)
Function of ribosomes
The site of protein synthesis.
Function of the vacuole
Filled with sap that contains nutrients such and glucose and helps to keep the cell turgid.
Similarities between plant and animal cells
Both contain: Nucleus, cell membrane, cytoplasm, Mitochondria, ribosomes.
Differences between plant and animal cells
Plants also contain: Chloroplasts, cell wall, vacuole
Chemical elements present in carbohydrates
Carbon, hydrogen and oxygen
Chemical elements present in proteins
Carbon, hydrogen, oxygen, nitrogen and Sulphur
Chemical elements present in lipids
Carbon, hydrogen and oxygen (fats and oils)
Describe the structure of a carbohydrate as a large molecule
Long chains of monosaccharides joined together. These could include starch and glycogen from simple sugars
Describe the structure of proteins as a large molecule
A sequence of amino acids joined together.
Describe the structure of lipids as a large molecule
1 part Glycerol and 3 parts fatty acid.
Practical to investigate if glucose is present in a food sample.
Mix the solution in a test tube
Heat in an 80 degree water bath for 5 minutes
Add 2-3 drops of Benedicts solution to mixture.
Brick red if present and green/yellow if not.
Practical to investigate if starch is present in a sample
Dip sample in water and then put on a white tile. Then add 2-3 drops of iodine solution and will go blue/black if starch is present.
Practical to investigate if protein is present in a sample.
Add Biuret reagent to the food sample and it will turn purple if it is present.
Practical to investigate if lipids are present in a sample.
Put to sample in a test tube, add ethanol and shake for 3 seconds, followed by the addition of a few droplets of water. Will turn cloudy if Lipids are present. This is known as the emulsion test.
What role do enzymes play in metabolic reactions
They are biological catalysts
Describe how temperature change can affect enzyme function.
When temperature increases, kinetic energy of the enzymes increase meaning a faster rate of reaction. When temperature passes 40 degrees, the active site denatures and the substrate can no longer fit into the active site and rate of reaction rapidly decreases.
Practical to investigate how enzyme activity can be affected by changes in temperature.
Set up 5 water baths at different temperatures (e.g. 0, 20, 40, 60, …)
Add 10cm cubed of 10% starch solution and 5cm cubed of 5% amylase solution into a boiling tube and heat in a water bath.
Every minute (from the point mixing occurs) take one drop of this mixture and add it to
one drop of iodine solution in the spotting tile.
When digestion is complete and no starch is present, iodine solution will stay orange
(rather than turning blue black.
Repeat this using water baths of different temperatures
Define diffusion and how it allows substances to move in/out of cells
The net movement of particles from areas of high concentration to low concentration areas. This allows substances such as oxygen to diffuse from the blood and across the cell membrane and into the cell
Define osmosis and how it allows substances to move in/out of cells
The movement of particles across a semi-permeable membrane (cell membrane) from areas of low concentration to high concentration. E.g. Blood to cell.
Define active transport and how it allows substances to move in/out of cells
The movement of molecules from areas of low concentration to high concentration using ATP. This could include plants using Active Transport in root hair cells to absorb mineral ions.
Factors affecting the rate of diffusion and osmosis
Temperature
Surface area to volume ratio
Distance
Concentration gradient
Why does surface area to volume ratio affect rate of movement of substances
The bigger the cell, the more of the substance being diffused it needs and if it has a lower surface area in ratio to the size of the cell, then there is less space for the substance to enter.
Why does distance affect rate of movement of substances
If the distance to diffuse/osmose is longer, then the time taken will be longer as well so a reduced rate of movement.
Why does temperature affect rate of movement of substances
Particles will have more kinetic energy when temperature is higher so the speed that particles move will be faster.
Why does concentration gradient affect rate of movement of substances.
The larger the concentration gradient the larger the net movement of particles will be from one area to another and therefore rate of movement will increase.
Describe the practical to investigate rate of osmosis.
Potato strips can be placed in sucrose or salt solutions of different concentrations.
If the solution has a higher water
potential, water will move into the potato chip and the mass will increase. If the solution has a lower water potential, water will move out of the potato chip and the mass will decrease. Osmosis will occur until the water potential
of the tissue and solution are the same; this causes a mass change.
Word equation for photosynthesis
Carbon dioxide + Water –> Glucose + Oxygen
Energy change during photosynthesis
Light energy –> Chemical energy
Balanced symbol equation for photosynthesis
6CO2 + 6H2O –> C6H12O6 + 6O2
How does varying concentration of carbon dioxide affect rate of photosynthesis
As CO2 concentration increases, Rate of photosynthesis increases.
How does varying temperature affect rate of photosynthesis
Similar to enzymes, it increases until the active site becomes denatured and then it decreases rapidly.
How does varying light intensity affect rate of photosynthesis
As light intensity increases, rate of photosynthesis increases due to more light being able to be absorbed.
list the layers of a leaf
Waxy cuticle
Upper epidermis
Palisade mesophyll
Spongy mesophyll
Lower Epidermis
Guard cells and stoma.
Explain how the structure of the leaf is adapted for photosynthesis
Waxy cuticle, upper epidermis and palisade are all transparent. Leaf is thin so short distance for gases to diffuse and high surface area so more stomata. Guard cells can change shape and alter the size of the stomata. Stomata can close to reduce water loss.
What elements are required to make chlorophyll, amino acids and stimulate plant growth
Growth - Mineral ions
Chlorophyll - Magnesium ions
Amino acids - nitrate ions
Practical to investigate photosynthesis, showing evolution of oxygen from a water plant, the production of starch and the requirements of light, carbon dioxide and chlorophyll.
Take a leaf and put it in boiling water for 1 minute. Turn off the Bunsen burner under the water and transfer the leaf into a test tube containing ethanol and place in the hot water. Soften the leaf by placing it in the hot water directly for a few seconds. Place leaf on a white tile and cover in iodine solution. To show that light is required, one leaf is covered with foil so the the leaf does not show black as it has no light. To show chlorophyll is required, a variegated leaf, in which the white parts of the leaf lacks chlorophyll, is used and starch is only produced in the areas that were green. To show carbon dioxide is required one leaf of a plant is enclosed in a conical flask (or plastic bag) containing soda lime to absorb the carbon dioxide and this leaf is compared to another enclosed
in a flask but without the soda lime. Only the leaf that had access to carbon dioxide produces starch.
Things needed for a balanced diet
Appropriate amounts of carbs, protein, lipids, vitamins, minerals, water and fibre.
Sources and functions of lipids
Meat, cheese are sources
Long term energy store
Used for insulation
Forms part of cell membrane
Sources and functions of carbohydrates
Wheat and rice - sources
Provides glucose for the body and helps store starch
Sources and functions of proteins
Meat, fish and eggs - Sources
Used for enzymes, haemoglobin and hormones
Sources and functions of Vitamin A
Liver, eggs, dairy - Sources
Used by the retina to produce pigments and is essential for embryos to develop
Sources and functions of vitamin C
Citrus fruits (Lemons, oranges, limes) - Sources
Helps cells to stick together in the lining of various organs.
Sources and functions of Vitamin D
Sunlight, liver, dairy and eggs - Sources
Helps the body to absorb calcium
How do energy requirements vary with activity levels, age and pregnancy
Increased activity levels results in increased energy requirements. Children need more energy than adults due to bodily growth and pregnant woman need more energy to be able to keep their foetus growing normally.
Function of the mouth
This is where ingestion occurs
Mechanical digestion - chewing
Chemical digestion - Amylase (saliva) produced
Function of the oesophagus
Pushes swallowed food down and into the stomach via peristalsis.
Function of the stomach
Breaks down food by releasing enzymes such as pepsin that breaks down protein into peptides. It is acidic as pepsin works best in these conditions
Function of the duodenum
Enzymes produced by the pancreas (Trypsin, amylase, lipase) provide the last stage of chemical digestion in the duodenum. The duodenum wall also produces maltase and peptidase. Bile is also put here.
Function and source of bile
Bile is produced in the Liver and neutralises the stomach acid and emulsifies lipids. It is stored in the gall bladder
Function of the ileum
It is where absorption begins. It is covered in villi and microvilli - large surface area which have one cell thick walls and there is a high concentration gradient for fast diffusion of nutrients.
Function of the colon
(large intestine)
Site of all reabsorption of water
Function of the rectum
Where faeces is stored before it can be egested from the anus.
Define peristalsis
The contraction of muscles that allows food to be pushed through the digestive system at an even speed.
Enzymes involved in starch to glucose.
Starch via amylase to maltose
Maltose via maltase to glucose
Enzymes involved in proteins to amino acids
Protein via pepsin and trypsin to peptides.
Peptides via peptidase to amino acids
Practical to investigate the energy content in a food sample.
Set the food sample on fire using a Bunsen burner and hold it under a a test tube with 20cm^3 of water and measure temperature of water beforehand. Hold the food sample until the flame buns out and measure the temperature increase of the water.
Where does ATP come from and what does it do?
It is a product of respiration and provides energy for cells.
Describe the differences between Aerobic respiration and anaerobic respiration.
Aerobic:
Uses oxygen
Large amount of ATP
Anaerobic:
Toxic waste products
Less ATP
Only glucose needed
Aerobic respiration word equation and symbol equation
Glucose + Oxygen –> Carbon Dioxide + Water
C6H12O6 + 6O2 –> 6CO2 + 6H2O
word equation for anaerobic respiration in plants and animals
plants: glucose –> ethanol + carbon dioxide
animals: glucose –> lactic acid + carbon dioxide
Practical to investigate evolution of carbon dioxide and heat from respiring seeds.
Place two thermos flasks and fill one with 10cm^3 of alive peas and the other with the same amount of dead peas where both groups of peas are soaked in Milton solution to kill bacteria. Then put a cotton wool plug at the end of the flask and a thermometer. We only see a temperature rise in the flask with alive peas. We could also use limewater to see if CO2 has been produced.
Key effects of smoking
Coronary Heart disease
Cancer (especially lung)
CO binds to haemoglobin and reduces amount of oxygen blood can carry
Emphysema
Bronchitis
Many many more…
Practical to investigate breathing in humans and the effect of exercise
Make two people of similar age, body type, etc… and measure the number of breaths they take for a minute at rest and then make them exercise for 5 minutes. Then measure the number of breaths they take in the first minute after exercise.
How do root hair cells absorb water
Via osmosis
Define Transpiration
Transpiration is the evaporation of water from the surface of a plant
Factors that affect rate of transpiration
Humidity, wind speed, temperature and light intensity.
What apparatus can be used to measure rate of transpiration of a plant
A potometer
Describe how to set up a potometer
The potometer must be set up under water - this prevents any air bubbles from entering the system and blocking the xylem.. Cut the stem of a shoot.
Put the shoot stem into the bung, grease the joint with plenty of petroleum jelly - this prevents water loss and air entry. Put the bung into the potometer. Make sure the tap is closed and it is full of water (no bubbles). Then lift the potometer out of the water. Leave the end of the capillary tube out of the water until an air bubble forms then put the end into a beaker of water. You can measure the transpiration rate as distance the bubble travels in five minutes (or the time taken for the bubble to travel a set distance). You should take a number of readings and
calculate a mean rate.
What do lungs excrete
Carbon Dioxide
What do kidneys excrete
Faeces and Urine
What does skin excrete
Urea
How does the kidney carry out its role of excretion
The kidney filters the blood and removes any excess materials and passes them to the bladder to be excreted.
Describe the structure of the nephron
Bowman’s Capsule, Glomerulus, Proximal Convoluted Tubule, Loop of Henle, Distal Convoluted Tubule, The Collecting Duct.
Describe ultrafiltration in the bowman’s capsule and the formation of the glomerular filtrate
A build-up of pressure in capillaries causes the formation of the glomerulus. The capillaries walls enable small molecules to diffuse across into the glomerular filtrate but larger molecules cannot do this and so stay in the blood.
Why does selective reabsorption occur as the PCT
The walls of the PCT are made of specialised cells that have a high surface area and lots of mitochondria allowing reabsorption of glucose, amino acids and other useful materials.
Composition of Urine
Made of Urea, Water and Ions
Role of FSH in menstrual cycle
Develops the follicle and matures the ovum
Role of oestrogen in the menstrual cycle
Inhibits FSH production
Role of LH in the menstrual cycle
Triggers ovulation
Role of Progesterone in menstrual cycle
Inhibits FSH and LH
Define Population
The amount of a living thing in a certain area
Define Community
All living things living inside a habitat
Define Habitat
The environment where things live
Define Ecosystem
Living things and their environment around them.
Practical to investigate the population of an organism using quadrats
Measure the area that you want to find the population for using a tape measure and then in that area set out two 10m tape measures at right angles to make an axes. Then generate pairs of random numbers to get coordinates. Place the quadrat down at these coordinates and count the number of the organism is in the quadrat. Repeat ten times. Then find an average number across all readings and multiply it by the amount of quadrats that can fit in the original area.
Define Biodiversity
The variety of organisms in a certain habitat.
Practical to investigate distribution of an organism in two different areas using quadrats
Set up a grid in both areas and use random sampling in both areas to find an average in both areas.
List of abiotic factors which affect the population size and distribution of organisms.
Temperature, carbon dioxide and oxygen concentrations, minerals in the soil.
List of biotic factors which affect the population size and distribution of organisms.
Concentration of prey/predators and the concentration of other organisms in an area.
List the different trophic levels
Producer, primary consumer, secondary, tertiary, quaternary and decomposers
How much energy is actually transferred from prey to predator
Roughly 10%.
The Nitrogen Cycle
The role of yeast in production of food including bread
The yeast anaerobically respires and causes the bread to rise by creating bubbles of Carbon dioxide.
Practical to investigate the role of anaerobic respiration by yeast in different conditions
Dissolve sugar in previously boiled water. Add yeast and mix to form a suspension and pour into a boiling tube. Then add a thin layer of vegetable oil to prevent oxygen entering. Then add a delivery tube to a test tube filled with limewater. Limewater will turn cloudy if carbon dioxide is present and this will show if yeast is respiring. Can change sugar solution with differing temperature, concentration of sugar or type of sugar to get different readings.
Role and name of bacteria used in the production of yogurt
Lactobacillus is used to create lactic acid during anaerobic respiration and makes the yogurt acidic.
