Biology Paper 1 Flashcards
What are the differences between a prokaryote and a eukaryote?
Prokaryotes do not contain a nucleus, whereas eukaryotes do. Prokaryotes have a cell wall, whereas eukaryotes do not.
Name the 5 common features of a plant and animal cell.
Cell membrane, cytoplasm, nucleus, mitochondria, ribosomes.
State the 3 features structures that a plant cell contains and an animal cell does not.
Chloroplasts, cell wall, vacuole.
What is the function of the nucleus?
Contains genetic material and controls the activities of the cell.
What is the function of the cell membrane?
To control the substances that move in and out of the cell.
What is the function of the cytoplasm?
Contains all the organelles and is the site of many chemical reactions.
What is the function of the mitochondria?
The site of respiration where energy is released.
What is the function of the ribosomes?
The site of protein synthesis, where new proteins are made.
What is the function of the permanent vacuole?
It contains cell sap and enzymes. It can also store excess water.
What is the function of a chloroplast?
It is filled with chlorophyll, absorbs light and is where photosynthesis happens.
What material makes up cell walls in plants?
Cellulose.
State why prokaryotes do not contain membrane bound organelles.
Membrane bound organelles are too large to fit in a prokaryote.
What is a specialised cell?
A cell that has specific features or adaptations to perform a particular job.
Describe how a sperm cell is adapted.
Tail/flagellum - for locomotion/movement
Acrosome - to digest the egg surace
Many mitochondria - for respiration to release energy to swim to the egg
Describe how a muscle cell is adapted.
Many mitochondria for respiration to release energy to the muscle for contraction.
Describe how a root hair is adapted.
Hairs/projections - to increase the surface area to absorb more water/nutrients.
No chloroplasts - not needed to photosynthesise.
Describe how a nerve cell is adapted.
Long axon - to carry messages long distances
Many dendrites to make any connections
Describe how a xylem cell is adapted.
Dead, hollow cells that form a tube.
Lignin for strength and to withstand water pressure.
Describe how a phloem cell is adapted.
Live cell, contains sieve plates to distribute sugar evenly throughout the plant.
Describe how a red blood cell is adapted.
No nucleus and a biconcave dip to carry more haemoglobin which binds to oxygen.
What is cell differentiation?
When a cell becomes a specialised cell
When do most cells differentiate in an animal?
Foetal stage
When do most cells differentiate in a plant?
They can differentiate at any times
In mature animals what is cell differentation used for?
Repair of damaged tissues or cells
Name 2 types of microscopes
Light/optical microscope
Electron microscope
State 2 advantages and disadvantages of a light/optical microscope
Advantages: Portable, easy to use, see colour, inexpensive, live specimens Disadvantages - 2D, low resolution, low magnification
State 2 advantages and disadvantages of an electron microscope
Advantages: 3D images, high magnification, high resolution Disadvantages - Expensive, black and white images only, specimen must be dead
What is meant by resolution or resolving power?
The fineness of detail that can be seen in an image. The higher the resolution of an image, the more detail it holds. The ability to distinguish between 2 points.
What is an order of magnitude?
A number to the base of 10, often used to make comparisons.
How do you calculate magnification?
Magnification = Image size / Actual size
How do you rearrange the equation to calculate the actual size of an image?
Actual size = Image size / Magnification
What is 1260000nm as standard form?
1.26 x 10-3m
What is 0.0000001m as standard form?
1 x 10 -7m
What is a stage micrometre?
A glass slide with a scale on it used to calibrate the eyepiece
What is a graticule?
A glass or plastic disc fitted into the eyepiece of a microscope used to estimate the size of a specimen
How do you rearrange the equation to calculate the image size?
Image size = Magnification x Actual size
What are genes?
A section of DNA that codes for a particular protein
In what arrangement do we usually find chromosomes?
In pairs
How many chromosomes does a human adult have?
46 or 23 pairs
What happens to the cell before it divides?
The nucleus disappears, chromosomes become short, fat and they double.
What is produced during mitosis?
Genetically identical daughter cells
What is produced during meiosis?
Gametes
What type of cell division can be called “double division”?
Meiosis
Why is mitosis important?
Growth, repair and maintaining the chromosomes number
What do we call a cell with 2 sets of chromosomes?
Diploid
What do we call a cell with 1 set of chromosomes?
Haploid
What type of cell is produced during meiosis in males and females?
Male - sperm
Female - egg
If a cell with a diploid number 24 undergoes meiosis, how many chromosomes would be in each daughter cell?
12
What is diffusion?
The movement of particles from an area of high concentration to an area of low concentration, down a concentration gradient.
What is osmosis?
The movement of water particles from a dilute solution to a more concentrated solution, through a partially permeable membrane
What is active transport?
The movement of particles against a concentration gradient, from a low concentration to a high concentration requiring energy.
State 3 substances that can move by diffusion in animal cells.
Oxygen, carbon dioxide and glucose
How can we increase the rate of diffusion?
Increase the concentration gradient, decrease the diffusion distance/thickness of surface, increase the surface area
How is a root hair cell adapted for osmosis?
Lots of hairs/projections that increase the
surface area so more water can be absorbed
How are cells in the small intestine adapted for active transport?
Many mitochondria to release
energy for active transport
What is required for active transport?
Energy
What is a concentration gradient?
The difference between two concentrations
Define the terms solute and solvent.
Solute- Soluble solid/ substance that dissolves
Solvent- A liquid that the dissolves the solute
What does it mean when the net movement of water is 0?
Water will not move
What are the differences between hypertonic, hypotonic and isotonic?
Hypertonic - less solute inside the cell, more outside
Hypotonic - more solute inside the cell, less outside
Isotonic - same amount of solute inside/outside cell
What is a tissue?
A group of specialised cells working together
What is an organ?
A group of tissues working together
What is a system?
A group of organs working together
State 3 examples of tissues in the digestive system and what each of them do.
Glandular - Releases enzymes and digestive juices
Muscular - Contract the stomach walls to churn the food
Epithelial - to line stomach
What is an enzyme?
A biological catalyst (which is a protein)
Name 2 environmental conditions that cause an enzyme active site to change
Temperature increase
Increase or decrease in pH
Name 3 digestive enzymes and what they break down
Lipase - breaks down lipids/fats
Amylase - breaks down starch
Protease - breaks down protein
Carbohydrase - breaks down carbohydrate
State 2 functions of bile
Emulsify fat
Neutralise stomach acid before food moves into the small intestine
What are the products when protein, fats and starch is broken down?
Protein - Amino acids
Fats - Fatty acid and glycerol
Starch - Glucose
What is the lock and key model?
The shape of the active site matches the shape of its substrate molecules. This makes enzymes highly specific
What does denatured mean?
When the shape of the enzymes active site changes and the substrate no longer fits
Where is bile produced and where is it stored?
Produced in the liver
Stored in the gall bladder
What substance transports substances around the body?
The blood
Name the 4 components of blood.
Red blood cells, white blood cells, plasma and platelets
Name the upper and lower chambers of the heart
Upper - Atria
Lower - Ventricles
What is the function of the coronary arteries?
To provide heart tissue with oxygen for respiration, which releases energy for the heart muscle to contract
State an adaptation of each blood vessel
Capillary - 1 cell thick, covers larger surface area
Artery - Elastic walls for vasoconstriction/vasodilation
Veins- contain valves to prevent back flow, large lumen
What structure protects the lungs?
Rib cage
State the pathway of air from the atmosphere to the blood
Nose/mouth, trachea, bronchi, bronchioles, alveoli, blood
What are the structures called where gas exchange happens?
Alveoli
State the red pigment that blood cells contain.
Haemoglobin
What is the function of the red pigment in blood?
Bind with oxygen and transport it to the respiring cells
Name the substances that are exchanged in gas exchange at the alveoli.
Oxygen moves into the blood stream and carbon dioxide moves into the alveoli
State the risks associated with surgical intervention in the treatment of heart disease
Death, rejection of organ transplant, clotting problems, thrombosis, infection
What is the function of the waxy cuticle?
To cover, protect and provide a waterproof layer
What is the function of the palisade mesophyll layer?
Where the majority of photosynthesis takes place
What is the function of the spongey mesophyll layer?
Where the majority of gas exchange takes place
What is the role of the guard cells?
To control the opening and closing of the stomata, which control water loss and gas exchange
How are palisade cells are adapted for their function?
Large, tall cells to absorb more light.
Lots of chloroplasts for photosynthesis.
What is the role of the xylem?
Carry water from the roots around the plant
How is the xylem adapted to its function?
Hollow tubes strengthened by lignin
What is transpiration?
The movement of water from the roots to the leaves, eventually leaving the leaves via evaporation
What is the role of the phloem?
To carry sugars from the leaves around the plant
How is the phloem adapted?
Elongated cells with pores in the end cell walls to aid the movement of dissolved sugars
What is translocation?
The movement of sugars from the leaves to the rest of the plant
How are plants adapted for gas exchange?
The structure of the leaf is adapted for gas exchange. The cells in the spongy mesophyll (lower layer) are loosely packed, and covered by a thin film of water. There are tiny pores, called stomata, in the surface of the leaf
What is meant by the term communicable disease?
A communicable disease is one that is spread from one person to another
Name 4 ways that a pathogen can be transmitted and then prevented
Through air, through water, direct contact (e.g. STDs), vectors.
Hand-washing, safer sex practices, vaccination, eradication of vectors.
State 4 types of pathogen.
Viruses, bacteria, protists, fungi
How do bacteria make you ill?
Bacteria may produce poisons (toxins) that damage tissues and make us feel ill
Why might viruses cause you more damage?
Viruses live and reproduce inside cells, causing cell damage
What is the role of the immune system?
If a pathogen enters the body the immune system tries to destroy the pathogen
What does a vaccine contain and how does it work?
A small quantity of dead or inactive forms of a pathogen.
It stimulates the white blood cells to produce antibodies.
If the same pathogen re-enters the body the white blood cells respond quickly to produce more of the correct antibodies quickly, preventing infection.
What is herd immunity?
The majority of the population is vaccinated against serious diseases, which can reduce the chance of people coming into contact with specific pathogens
How do antibiotics work?
Killing infective bacteria inside the body through many different ways e.g. preventing the cell wall from forming or preventing DNA from being replicated
Describe the stages involved in drug trials.
Preclinical testing is done in a laboratory using cells, tissues and live animals.
Clinical trials use small numbers of healthy volunteers and patients. Very low doses of the drug are given at the start of the clinical trial
If the drug is found to be safe, further clinical trials on larger groups of healthy volunteers and patients are carried out to find the optimum dose for the drug.
What is meant by a double blind trial?
In double blind trials, some patients are given a placebo. Neither the doctor nor patient know whether they have been given a placebo in order to reduce potential bias.
What is a placebo?
A substance that has no therapeutic effect, used as a control in testing new drugs
What is meant by the term non communicable disease?
Diseases that develop and are not transferred between people or other organisms
Name 3 examples of non-communicable diseases.
Cancer, diabetes, genetic diseases and conditions, heart disease, neurological disorders
What is a risk factor?
Is something that can increase the chances of developing a non-communicable disease
State 3 risk factors.
Diet, lifestyle, stress, situations that may occur in a person’s life (trauma)
What is cancer?
A disease caused by normal cells changing so they grow and divide in an uncontrollable way that causes a tumour to develop
Name 2 types of tumours.
Benign and malignant
What is a correlation?
A relationship between 2 sets of data, such that when one changes you would expect the other to change
State 3 effect of smoking.
Cancers, heart disease, COPD/pulmonary disease, diabetes, increased chances of a blood clot or stroke, addiction, narrowing or arteries, pneumonia, emphysema, discolouration of skin
State the long term effects of alcohol abuse.
High blood pressure, stroke, pancreatitis, liver disease, liver cancer, mouth cancer, depression dementia, sexual problems, infertility
What are the short term effects of alcohol?
Increased heart rate, dilation of blood vessels, effects the brain (judgement, coordination and decision making) blurred vision, slower reaction time, slurred speech, dehydration, vomiting
State the potential effects of obesity.
Type II diabetes, coronary heart disease, cancer, stroke, depression and low self-esteem
What are the differences between type I and II diabetes?
Type I - usually develops during childhood, pancreas stops making insulin, controlled by injections and a good diet.
Type II - usually develops in adults who have poor lifestyles and are overweight, the body no longer responds to insulin due to damages beta cells, controlled with exercise and a good diet.
Write a word and balanced symbol equation for
photosynthesis.
W: Carbon dioxide + water - Glucose + Oxygen
S: 6C02 + 6H20 -> C6H12O6 + 6O2
Where does photosynthesis take place in a cell?
Chloroplast
What type of reaction is photosynthesis and why?
Endothermic because the leaf absorbs energy from sunlight to turn carbon dioxide and water into oxygen and glucose
Name 4 limiting factors of photosynthesis.
Light intensity, carbon dioxide concentration amount of chlorophyll and temperature
State 3 ways that glucose is used in a plant.
- Respiration
- Making new proteins
- Making cellulose for plant cell walls
- Stored as starch
- Active transport
What minerals are absorbed from the soil to help a plant?
Magnesium and nitrate (for chlorophyll production and growth)
What is respiration and where in a cell does it happen?
Respiration is the process by which organisms break down glucose (from sugars and carbohydrates in their food) in order to release energy. It occurs in the mitochondria
Write a word and balanced symbol equation for respiration.
W: Glucose + Oxygen Carbon dioxide + Water
S: C6H12O6 + 6O2
-> 6CO2 + 6H2O
State the word equation for anaerobic respiration in a)plants and b) animals.
a) Glucose › Ethanol + Carbon dioxide
b) Glucose > Lactic acid
Why is respiration important?
Mammals and birds need energy to maintain a constant body temperature. Energy is also needed for the following life processes: growth, cell division, muscle contraction, protein synthesis, active transport, nerve impulses and building new molecules.
What is oxygen debt?
The amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells
What is metabolism?
The sum of all the reactions in a cell or the body
What is a stem cell?
An undifferentiated cell that has the potential to specialise.
Define adult stem cell.
Stem cells that can only differentiate into a specific type of cell
Name another type of stem cell found in animals.
Embryonic stem cells
Where is the answer from 22.3 found?
Embryos, umbilical cord
Where are adult stem cells found?
Bone marrow
Which type of stem cells would scientists prefer to use and why?
Embryonic stem cells as they can differentiate into many types of cell
What is a plant stem cell called?
Meristem
Where would you find plant stem cells?
Meristem
How are plant stem cells different to adult stem cells or embryonic stem cells?
They can differentiate at any time
What are the advantages of using adult stem cells?
Easier to obtain, effective, no ethical issues, abundant supply, little or no problems with immune rejection
What are the advantages of using embryonic stem cells?
Can differentiate into any type of cell, potential to cure diseases such as blindness, diabetes and cancers
Why might people be against the use of stem cells?
Ethical reasons surrounding the use of embryos, may not know the side effects, potential rejection
