Biology Flashcards
Explain the characteristics of a light microscope.
- Uses a beam of light to form an image.
- Can magnify objects up to 2000 times. (School ones usually only go up to 400 times.)
- Can be used to view living objects.
- Relatively cheap and easy to move around.
Explain the characteristics of an electron microscope.
- Uses a beam of electrons to form an image.
- Can magnify objects up to 2,000,000 (2 million) times.
- Cannot be used for living objects.
- Very expensive and need to be kept in special conditions.
Which type of microscopes are usually used in schools?
Light microscopes.
What does resolving power mean for a microscope?
The measure of how close 2 dots can be distinguished through a microscope on an object.
What is the equation for magnification?
Magnification = image size / object size
What is the purpose of a nucleus?
To control the cell’s activities.
What is contained in the nucleus of a cell?
Genes on chromosomes which carry instructions for making proteins.
What is the purpose of cytoplasm?
A liquid gel in which organelles are suspended, also the site of many chemical reactions.
What is the purpose of the cell membrane?
To control movement of substances into and out of the cell.
What is the purpose of the mitochondria?
Site of energy transfer for aerobic respiration.
What is the purpose of ribosomes?
Organelle where protein synthesis takes place.
What is the purpose of cell walls?
A cellulose structure to provide structure to the cell.
What is the purpose of chloroplasts?
They contain chlorophyll for photosynthesis.
What is the purpose of the permanent vacuole?
To contain cell sap, keeping the cell rigid and helps support the plant.
What organelles are found in animal cells?
- Nucleus
- Cytoplasm
- Cell membrane
- Mitochondria
- Ribosomes
What organelles are found in plant cells?
- Nucleus
- Cytoplasm
- Cell membrane
- Mitochondria
- Ribsomes
- Cell wall
- Chlorophyll / Chloroplast
- Permanent vacuole.
What is the difference between a eukaryotic and prokaryotic cells?
Eukaryotic cells contain a nucleus holding genetic material, whereas prokaryotic cells have plasmids (DNA loops) containing genetic material. Prokaryotic cells are also smaller than eukaryotic cells.
What do nerve cells do?
Carry electrical impulses around the bodies of animals.
What are the adaptations of a nerve cell?
- Dentrites to make connections to other nerve cells.
- An axon to carry the impulse from one place to another.
- Nerve endings or synapses which pass impulses to other cells by producing transmitter chemicals.
- Many mitochondria in synapses to transfer the energy needed to make transmitter chemicals.
What do muscle cells do?
They contract and relax to move around your body.
What are the adaptations of a muscle cell?
- Special proteins that slide over each other.
- Many mitochondria to transfer the energy required for chemical reactions.
- A store of glycogen which can be broken down and used in respiration to transfer energy.
What do sperm cells do?
Carry genetic information from the male parent to the female parent. (The egg.)
What are the adaptations of a sperm cell?
- Long tail (flagellum) which whips side to side to move the sperm.
- A middle section full of mitochondria to transfer energy needed by the flagellum to move.
- An acrosome to store digestive enzymes to break down the outer layers of the egg.
- A large nucleus to contain genetic information.
What do root hair cells do?
Absorb water and mineral ions in the soil.
What are the adaptations of a root hair cell?
- Large surface area for quick abosorbing.
- Large permanent vacuole to speed up movement of water through osmosis.
- Many mitochondria to transfer the energy required for active transport.
What do photosynthetic cells do?
Absorb sunlight to make food.
What are the adaptations of a photosynthetic cell?
- Chloroplasts to trap light for photosynthesis.
- Continuous layers in the leaf and outer layers of the stem.
- Large permanent vacuole to keep the cell rigid.
What do xylem cells do?
Transports water and mineral ions from the roots to the stem and leaves. It also contains xylem tissues which supports the plant.
What are the adaptations of a xylem cell?
- Long hollow tubes for water and mineral ions to move up.
- Spirals and rings of lignin to make the tubes of xylem very strong.
What does the phloem cell do?
Tissue which transports food made by photosynthesis to the rest of the plant.
What is diffusion?
Movement of particles from an area of high concentration to an area of low concentration, along the concentration gradient.
What is osmosis?
Movement of water from a dilute to concentrated solution.
What is active transport?
Movement of particles from an area of low concentration to an area of high concentration. Going against the concentration gradient.
Which one(s) require energy out of:
1) Diffusion
2) Osmosis
3) Active transport
1) No energy
2) No energy
3) Requires energy
What is the word for 2 solutions with the same concentrations?
Isotonic
What does isotonic mean?
2 solutions with the same concentration.
What is the word for a solution with higher concentration?
Hypertonic.
What does hypertonic mean?
A solution with a higher concentration.
What is the word for a solution with a lower concentration (dilute)?
Hypotonic
What does hypotonic mean?
A solution with a lower concentration.
What is turgor pressure?
When no water can enter a cell due to the pressure inside.
What is plasmolysis?
When the cell membrane pulls away from the cell wall.
What is cystic fibrosis?
When a person produces abnormally thick mucus because the active transport system in their mucus cells aren’t working properly.
Where is oxygen inhaled into?
The alveoli in the lungs.
What is the stomata in plants?
Tiny openings (pores) in plant tissues which allow gas exchange.
Where is villi found and what does it do?
It is found in the small intestine and it uses it’s large surface area to absorb food molecules.
What is mitosis?
When a cell splits into 2 identical cells.
Why is mitosis important?
It allows living organisms to grow, but also allows body repairs and replacing cells that have died.
What is the cell cycle?
The steps in the process of cell division. (Mitosis.)
What are the 3 stages of the cell cycle?
1) Cell grows and DNA (chromosomes) replicate. Increase in number of sub-cellular structures
2) Complete set of chromosomes is pulled to each end of the cell. Nucleus divides to create 2 nuclei (mitosis)
3) Cytoplasm and cell membrane divides to form 2 identical daughter cells
How many pairs of chromosomes do human body cells have?
23 pairs of chromosomes.
(Or 46 singular chromosomes.)
(23 come from the female parent, and 23 come from the male parent.)
How many chromosomes do egg cells and sperm cells have each?
23 chromosomes.
(They combine to form 46 chromosomes, enough for a normal body cell.)
What is cell differentiation?
When a cell changes into different types of cells to carry out functions.
(i.e. they specialise.)
What are unspecialised cells called?
Stem cells
What is a meristem?
An actively dividing plant tissue.
What is cloning?
Producing genetically identical offspring.
Why is it difficult to clone animals?
Because once cells are differentiated, they cannot become unspecialised again.
What is a zygote?
The product of an egg cell and sperm cell fusing. The zygote divides many times to form a ball of cells, known as an embryo.
Where can adult stem cells be found?
In the bone marrow.
What conditions can human stem cells be used to treat?
- Paralysis by differentiating stem cells into nerve cells.
- Macular degeneration in the eye to restore lost vision.
- Diabetes, by producing cells which are sensitive to blood sugar and can produce insulin.
What are the benefits of cloning plants?
- Rare plants can be saved from extinction.
- Large populations of plant species can be produced for research.
- Large numbers of exotic plants can be produced for sale.
- Plants can be produced with special features such as disease resistance.
Where are embryonic stem cells found?
In the inner layers of the ball of cells which forms an embryo.
Where are stem cells found in plants?
In the meristems.
What are some of the issues from stem cell production?
- Some people believe that taking stem cells from an embryo is violating its rights.
- Some people, usually in religions, believe that producing stem cells is interfering with the natural process of reproduction.
- Some people think that money is being wasted on stem cell research.
- Scientists find it difficult to ‘persuade’ stem cells to differentiate, development is slow and expensive.
- Embryonic stem cells divide rapidly and there are fears that it could cause cancer.
- Adult stem cells could transmit viruses or trigger and immune response.
What is therapeutic cloning?
The process of producing an embryo with genes which are identical to the patient, and then using embryonic stem cells for medical treatment.
What is an advantage of theraputic cloning?
The cells produced are genetically identical to the patient so they are less likely to be rejected.
What is a tissue?
A group of cells with similar structures and functions which work together to carry out a task.
Name the 4 types of tissues in animals and their function.
1) Muscular: movement.
2) Glandular: production of enzymes and hormones.
3) Epithelial: covering the outsides of organs and structures.
4) Connective: supports, protects and provides structure to other tissues and organs.
What is an organ system?
A group of organs working together to carry out a task.
(For example, the digestive system.)
What does the digestive system do?
Changing food that you eat from insoluble molecules to soluble molecules, then absorbing them into the blood.
Where is bile produced and where is it stored?
It is produced in the liver and stored in the gall bladder.
What does the small intestine do?
Helps further digest food from the stomach, then absorbs nutrients through the villi.
What does the large intestine do?
Absorbs remaining water
What are some adaptations of villi?
- Very large surface area.
- Thin wall for short diffusion path.
- Good blood supply to carry food away to maintain a concentration gradient.
What are carbohydrates made of?
Units of sugar.
What are lipids?
Molecules made from 3 molecules of fatty acids linked to a molecule of glycerol.
What are proteins made of?
Long chains of amino acids.
What is an enzyme?
A biological catalyst. They speed up reactions.
What is an active site?
The area of an enzyme where substrates fit.
(Specific molecules can fit in each active site. Lock and key theory.)
What can enzymes do to substrates?
- Build large molecules from many small ones, such as building starch from glucose molecules.
- Change one molecule into another, such as converting sugars.
- Break down larger molecules into smaller ones.
What is metabolism?
The sum of all chemical reactions that take place in the body. These reactions break and/or build up molecules.
What is denaturing in enzymes?
When the temperature gets too high, the shape of the active site changes. This will slow down or completely stop an enzyme from functioning as substrates won’t be able to fit in the active site.
What is the effect of pH on an enzyme?
If the pH is too high or too low, the forces which hold together the proteins in an enzyme weaken and the enzyme changes shape. This will denature the enzyme.
What are the 3 words used to describe pH?
1) Acidic
2) Neutral
3) Alkaline
What are the 3 digestive enzymes?
1) Amylase (carbohydrase)
2) Proteases
3) Lipase
What temperature to enzymes work best at?
37°C
(Body temperature)
What pH conditions do the 3 enzymes work best at?
Protease: Acidic.
Amylase and lipase: Slightly alkaline.
What does bile do?
- Neutralises stomach acid.
- Makes the small intestine slightly alkaline.
- Emulsifies fats (breaking down fats into smaller droplets) to increase surface area.
What are the contents of blood?
- Plasma
- Red blood cells
- White blood cells
- Platelets
What does plasma do in the bloodstream?
It is the watery fluid which holds all the components of blood flow.
What do red blood cells do?
It uses haemoglobin to bind with oxygen so that it can be carried around the body.
What do white blood cells do?
They form the body’s defence system against microorganisms.
What do platelets do?
They help clot blood at the site of a wound.
What are the adaptations of a red blood cell?
- Bioconcave discs for large surface area.
- Red pigment called haemoglobin to bind with oxygen which forms oxyhaemoglobin.
What do arteries have and do?
- Carry blood away from the heart at a high pressure
- They have thick walls containing muscles and elastic tissues.
- Small lumen
What are the 3 types of blood vessels?
- Arteries
- Veins
- Capillaries.
What do veins have and do?
- Carry blood towards the heart at a low pressure
- Thin walls
- Large lumen
- Contain valves to prevent backflow.
What do capillaries have and do?
- Carries blood to tissues and cells
- Connects arteries and veins
- One cell thick for short diffusion path
- Very narrow lumen
What is a double circulatory system?
A blood transportation system with 2 parts. One carrying blood to the lungs and back to the heart to collect oxygen. And another to carry oxygenated blood to your organs and back to the heart.
What are the 4 chambers of the heart and where would they be on a diagram?
- Right atrium (top left)
- Left atrium (top right)
- Right ventricle (bottom left)
- Left ventricle (bottom right)
What does the right atrium do?
Receives deoxygenated blood from the body from the vena cava.
What does the left atrium do?
Receives oxygenated blood from the lungs from the pulmonary vein.
What does right ventricle do?
Pumps deoxygenated blood into the pulmonary artery to the lungs.
What does the left ventricle do?
Pumps oxygenated blood into the aorta to be transported around the body.
What stops blood from flowing in the wrong direction?
Valves.
What do the coronary arteries do?
Supplies the heart muscles with oxygenated blood.
(If it is blocked, or narrowed, it will likely cause coronary heart disease.)
How do doctors open up arteries?
With a stent.
What could leaky valves potentially do?
Blood could flow in the wrong direction. (Backflow)
What is the beats per min of a pacemaker and where would it be located?
70 beats per min.
Located in right atrium.
What are artifical hearts used for?
- Keeping patients alive while waiting for a heart transplant.
- Allowing heart to rest as an aid to recovery.
What is a disadvantage of artificial hearts?
The patient needs drugs to prevent the blood from clotting.
What are the adaptations of alveoli?
- Large surface area
- Thin walls for short diffusion path
- Good blood supply
Where does oxygen diffuse into after the alveoli?
Capillaries in the lungs.
What is a palisade mesophyll?
A plant tissue which has many chloroplasts and can photosynthesise.
What is a spongy mesophyll?
A plant tissue with some chloroplasts, but many air spaces between cells and a large surface area for diffusion of gases.
What is translocation?
When the phloem tissue in a plant carries dissolved materials from the leaves to the rest of the plant.
What are the 2 transportation tissues in plants?
- Xylem
- Phloem
What does a guard cell do?
Controls the size of the stomata in plants, therefore, changing the rate of gas diffusion.
What is transpiration?
When water vapour diffuses out of the plant through the stomata.
What 4 factors affect rate of photosynthesis and how?
- Temperature. When temperature increases, molecules move faster, making rate of diffusion faster too.
- Humidity. The rate of diffusion of water is quicker in dry air than damp air.
- Wind. Windy conditions increase rate of evaporation and blow away water vapour, increasing concentration gradient.
- Light intensity. More light increases rate of photosynthesis.
How do plants control water loss?
- Waxy, waterproof cuticles on leaves.
- Most of the stomata are under the leaves.
- Wilting, as surface area will decrease.
- Stomata can close which can reduce water loss but also reduce rate of photosynthesis.
What is a communciable disease?
A disease which can be spread from one organism to another.
What is a non-communicable disease?
A disease which cannot be spread from one organism to another.
What factors can affect health?
- Diet
- Stress
- Living conditions
- Gender
- Financial status
- Ethnicity
- Number of people in contact with
Where do viruses live in the body?
Inside cells.
What is a pathogen?
A microorganism which can cause disease.
What are the 4 types of pathogens?
- Virus
- Bacteria
- Fungi
- Protist
How does bacteria make you feel ill?
Producing toxins in the body and potentially damaging body cells.
How do viruses harm us?
They reproduce inside cells, damaging and destroying them.
How can pathogens be spread?
- Through the air
- Direct contact
- Through water
What is binary fission?
The process by which prokaryotic cells such as bacteria divide.
What is agar gel used for?
A substance which acts as a culture, containing nutrients, for the growth of bacteria and other microorganisms
Why should microorgansims be prevented from leaving the petri dish?
In case there is a mutation, producing a new and dangerous pathogen.
In what ways can bacterial growth be prevented?
- Raising or lowering temperature
- Disinfectants
- Antiseptics
- Antibiotics
Who discovered that infections could be transferred and what did he tell people to do to help prevent this?
Ignaz Semmelweiss
He told his staff to wash their hands between treating patients.
Who showed that microorganisms can cause disease and what did he develop afterwards?
Louis Pasteur
He developed vaccines against anthrax and rabies.
In what ways can the spread of communicable diseases be prevented?
- Good hygiene
- Isolating infected people
- Destroying or controlling vectors
- Vaccinations
What is the main symptom of measles?
Red skin rash
What does tobacco mosaic virus (TMV) do and how is it spread?
- Discolours leaves and destroys cells, preventing photosynthesis.
- Spread by contact between diseased and healthy plants and by animal vectors.
What type of pathogen is salmonella?
Bacteria
Where can salmonella be found?
Raw meat, poultry, eggs and egg products.
What are some symptoms of salmonella food poisoning?
- Fever
- Abdominal cramps
- Vomiting
- Diarrhoea
What type of pathogen is rose black spot?
Fungi
What is a symptom of rose black spot?
Purple or black spots on leaves.
What type of pathogen is malaria?
Protist
What are the 4 main components of the body which defend us from pathogens?
- The skin
- The respiratory system
- The stomach
- White blood cells
How does the skin protect us from pathogens?
- Acts as a barrier by covering tissues underneath.
- Produces antimicrobial secretions to kill pathogenic bacteria.
- Heals quickly when cut using blood clots.
How does the respiratory system protect us from pathogens?
- Hair and mucus in the nose trap pathogens and dirt particles.
- Trachea and bronchioles secrete mucus to trap pathogens.
- Cilia beat to waft the mucus back up to the throat where it is swallowed.
How does the stomach protect us from pathogens?
- Produces acid which kills pathogens in the mucus you swallowed and in the food you eat.
How do white blood cells protect us from pathogens?
- Ingesting pathogens (phagocytosis)
- Producing antibodies
- Producing antitoxins
How do aphids harm plants and how can they be stopped?
Aphids use their sharp mouths to feed on sugar-rich sap in the phloem, taking the plants nutrients and weakening it.
They can be stopped using chemical pesticides or biological pest control such as ladybirds to eat aphids and their larvae.
What are the 2 main mineral deficiencies in plants, why are they needed, and happens when not provided?
Nitrate: Converts sugars to protein. Plant will not grow properly when not provided. (Stunted growth.)
Magnesium: Used to make chlorophyll. Plant’s leaves will turn yellow when not provided (chlorosis), so less photosynthesis and less growth.
What are the physical barriers of a plant and what do they do?
Cellulose cell walls: strengthens the plant to resist invasions.
Tough waxy cuticle: barrier to pathogen entry.
Bark on trees: it is a layer of dead cells on the outside of stems for a protective layer.
What are the chemical barriers of a plant and what do they do?
Antibacterial chemicals: protects plants against pathogens.
Poisons: deters herbivores.
What adaptations do plants have to avoid being eaten?
- Poisons
- Thorns
- Hairy stems / leaves
- Dropping or curling when touched
- Mimicry
What is a vaccine and what do they do?
A dead or inactive form of a pathogen. They are injected into the body and white blood cells produce antibodies for it as if it was the active form. The white blood cells can now produce antibodies much faster.
What is herd immunity?
When not all, but most of a society is vaccinated against a pathogen.
Why are treatments for viruses difficult?
They live inside cells, so treatment on the viruses could damage cells.
What antibody did Alexander Fleming discover?
Penicillin from the mould Penicillium
What drugs can be extracted from foxglove plants?
Digitalis and digoxin.
Where does aspirin come from?
Willow tree bark
What is preclinical testing?
Tests for drugs carried out in laboratories on cells, tissues or organs and then tested on animals.
What are clinical trials?
Drug testing on healthy volunteers and then patients.
What is placebo?
An inactive substance used to represent a drug to use as a control.
What are the basic steps to making monoclonal antibodies?
1) Combine mouse lymphocyte with a tumour cell to make a hybridoma.
2) Hybridoma cells divide to make a large number of identical cells that produce the same antibodies.
3) The antibodies are collected and purified.
What can monoclonal antibodies be used for?
- Treating diseases
- Pregnancy tests
- Disease diagnosis
- Monitor hormone levels
- Locate specific molecules by adding fluorescent markers to a monoclonal antibody
What is are the advantages and disadvantages of monoclonal antibodies?
Advantages
- Target diseased cells without harming healthy cells.
Disadvantages
- Side effects
- Expensive
What can monoclonal antibodies do against diseases?
- Target specific antigens on certain cancer cells.
- Carry radioacive substances, toxic drugs or another chemical directly to cancer cells without damaging other cells.
- Trigger the immune system to recognise and destroy cancer cells.
- Block receptors on the surface of cancer cells to stop them from dividing.
What is a causal mechanism?
When 2 factors have a consistent correlation.
What factors could increase chance of diseases?
- Age
- Genetics
- Lifestyle (like diet, activities and inhaling carcinogens)
- Envirionmental factors
What is a tumour?
A mass of abnormally growing cells.
What is a:
1) Benign tumour
2) Malignant tumour
Benign
A tumour that grows in one place. Doesn’t invade other tissues but can be dangerous if it grows in tissues like the brain.
Malignant
A tumour which can spread to healthy tissues through the bloodstream, causing secondary tumours.
What can cause cancer?
- Genetics
- Carciogens (smoking)
- Ionising radiation
- Virus infections
What 2 methods can treat cancer?
- Radiotherapy
- Chemotherapy
What does tobacco smoke contain?
- Nicotine (addictive substance)
- Carbon monoxide (toxic gas)
- Tar (Sticky black substance which accumulates in lungs and is a carcinogen.
- Chemicals that anaesthetise the cilia
What are the problems caused by smoking?
- Carbon monoxide carried instead of oxygen in the blood.
- A pregnant woman’s baby will receive less oxygen.
- Mucus containing dirt and pathogens build up in airways.
- Tar and other chemicals inflame the bronchi (causing bronchitis.)
- Tar can damage the alveoli.
- Tar causes cancers in the resiparatory system.
- Cardiovascular disease.
What can obesity lead to?
- Type 2 diabetes
- High blood pressure
- Heart disease
How does regular exercise reduce the chance of cardiovascular disease?
- Lowers blood choleterol levels.
- Reduces fatty deposits in the blood vessels.
- Building muscle tissue, increasing metabolic rate.
- Improving blood supply to heart.
What part of a cell absorbs sunlight for photosynthesis?
Chloroplasts (Chlorophyll)
What is the word equation for photosynthesis?
Carbon dioxide + Water
—-> Glucose + Oxygen
(The arrow is also light energy.)
What is some glucose converted into and why?
Into insoluble starch for storage.
How are leaves adapted for photosynthesis?
- Broad and flat leaves for large surface area.
- Thin so the diffusion path is short.
- Photosynthetic leaves contain chlorophyll.
- Veins contain xylem, bringing water.
- Veins contain phloem, taking glucose away.
How might the rate of photosynthesis be slowed down?
- Lack of light
- Too cold (enzymes won’t work efficiently)
- Not enough carbon dioxide
What are the uses of soluble glucose?
- Converted into insoluble starch for storage
- Respiration
- Conversion into fats and oil for storage
- Produces cell walls to strengthen cell walls
- Produce amino acids
What type of reaction is aerobic respiration?
Exothermic
(Glucose and oxygen transfer energy)
What is the word equation for aerobic respiration?
Glucose + Oxygen
—-> Carbon dioxide + Water
What might energy be used for in an organism?
- Build larger molecules from smaller ones
- Muscle contraction
- Maintaining constant body temperature
- Move materials such as mineral ions with active transport
- Building sugars, nitrates and other nutrients inot amino acids and then proteins in plants.
How does the body respond when exercising?
- Increased heart rate
- Blood vessels supplying the muscles dilate (widen)
- Rate of breathing and depth of breathing increase.
What do muscles store glucose as?
Glycogen
What is anaerobic respiration?
When glucose is not completely broken down and lactic acid is produced. This happens when there is a lack of oxygen.
How is lactic acid removed from muscles?
Lactic acid in muscles are transported to the liver via the bloodstream and then converted back to glucose
What do plants produce when respiring anaerobically?
Ethanol and carbon dioxide
What is anaerobic respiration in yeast cells called?
Fermentation
What are the roles of the liver?
- Turning excess amino acids into ammonia through deamination. The ammonia is then turned into urea, which is then excreted in the urine.
- Poisonous substances are detoxified.
- Old red blood cells are broken down into iron to make new red blood cells.
- Lactic acid is transported to the liver through the blood and converted into glucose.
- Excess glucose is stored as glycogen in the liver.
What is homeostasis?
When your body maintains a constant internal environment.
What internal conditions are maintained in homeostasis?
- Body temperature
- Water content
- Blood glucose concentration
What are effectors?
Muscles or glands which bring about a response to a stimulus.
How is information passed through nerve cells?
Electrical impulses through neurones
What does the central nervous system compose of?
- Brain
- Spinal cord
What is the difference between sensory neurones and motor neurones?
Sensory neurones carry electrical impulses to the CNS, motor neurons carry electrical impulses away from the CNS.
What is the full route through the nervous system?
stimulus –> receptor –> sensory neurone –> CNS –> motor neurone –> effector –> response
What is the difference between a reflex action and a normal reaction?
Reflex actions are sub-conscious and go through the spinal cord.
Normal reactions are conscious and go through the brain.
How are messages sent across the spinal cord?
Electrical impulses from the sensory neurone are neurotransmitted across a synapse and gets turned into a chemical impulse to go through the relay neurone. The chemical impulse then gets neurotransmitted across another synapse and gets turned into an electrical impulse and moves down the motor neurone.
What does the cerebal cortex do?
Concerned with consciousness, intelligence, memory and language.
What does the cerebellum do?
Concerned with coordination of muscular activity.
What does the medulla do?
Concerned with unconscious activities, like heartbeat and breathing.
What does the pituitary gland do?
Acts as a master gland, produces many hormones.
What does the hypothalamus do?
Helps maintain the body temperature using the thermoregulatory centre.
How do scientists study the brain?
- Studying patients with brain damage.
- Electrically stimulating parts of the brain.
- MRI scans.
What are some problems with treating the brain?
- Drugs do not always pass through the membranes surrounding the brain.
- The function of each area of the brain is not fully understood.
How do muscles in the iris adapt to different light levels?
Dim Light
Circular muscles slacken. Radial muscles pulled tight. Pupil dilates.
Bright Light
Circular muscles pulled tight. Radial muscles slacken. Pupil constricts.
How do muscles in the lens adapt to objects at different distances?
Near Objects
Suspensory ligament relaxes. Ciliary muscle contracts. Lens becomes short and fat.
Distant objects
Suspensory ligament pulled tight. Ciliary muscle relaxes. Lens becomes long and thin.
Where should light ideally be focused onto in the eye?
The retina
How are messages from the eye sent to the brain?
When light hits the retina, light sensitive cells are stimulated. They send impulses to the brain through sensory neurones in the optic nerve.
What is accomodation?
The process of changing the shape of the lens to focus on near and distant objects.
What is:
1) Myopia
2) Hyperopia
1) Short-sightedness
2) Long-sightedness
How can bad eyesight be rectified?
- Glasses
- Contact lenses
- Laser eye surgery
- Lens replacement
What is the endocrine system?
A system made of glands that secrete hormones into the bloodstream.
What is the male and female sex hormone?
- Male: Testosterone
- Female: Oestrogen
Where is insulin produced, when is it produced and what does it do?
- Produced in the pancreas.
- Produced when there is excess glucose in blood.
- Causes glucose to convert into glycogen and move from bloodstream to cells.
What is glucose stored as in:
1) Animals
2) Plants
Animals: As glycogen in the liver and muscles.
But when these stores are full, glucose is stored as lipids which can make a person obese.
Plants: As starch
Where is glucagon produced, when is it produced and what does it do?
Produced in the pancreas.
Produced when there is too little glucose in the blood.
Causes glycogen in the liver to be changed back to glucose and released back into the blood.
What is the difference between type 1 diabetes and type 2 diabetes?
Type 1 Diabetes
This type is genetic. It happens when the pancreas produces too little or no insulin. Blood glucose level will be very high.
Type 2 Diabetes
This type is not genetic. It happens when the body does not respond to its own insulin. One significant factor is obesity.
How can type 1 diabetes be treated?
- Insulin injections
- Pancreas transplants
- Using embryonic stem cells to produce insulin producing cells.
- Genetically engineering the pancreas.
How can type 2 diabetes be controlled?
- Diet
- Exercise
- Reducing carbohydrate intake
- Drugs prescribed by doctors
What is a negative feedback loop?
A process where a effector causes an opposite output in order to maintain the ideal level of what is being regulated.
What is thyroxine?
- Hormone produced by thyroid gland in neck.
- Controls metabolic rate
- Controls how much oxygen is used by tissues
- Controls how the brain of a growing child develops.
- Important in growth and development.
What is adrenaline?
- Hormone produced by adrenal gland above kidneys.
- Released when stressed, frightened or angry for preparation for a response.
- Causes a ‘fight or flight’ reaction.
What does adrenaline do to the body?
- Increased heart rate
- Increased breathing rate
- Glycogen in liver converted to glucose to respire
- Pupils dilate to let in more light
- Mental awareness increases
- Increased flow in blood containing extra glucose and oxygen to limb muscles
What are primary sexual characteristics?
Sexual organs which babies are born with.
What are secondary sexual characteristics?
Sexual organs which develop during puberty.
How does a female’s body change during puberty?
(Name as many as you can)
- Growth spurt
- Underarm and pubic hair
- Breast development
- External genitals grow
- Body fat is deposited in hips and upper thighs
- Brain matures
- Mature ova form at the start of every month
- Uterus grows and becomes active
- Menstruation begins
How does a male’s body change during puberty?
(Name as many as you can)
- Growth spurt
- Underarm, pubic and facial hair
- Larynx gets bigger and voice breaks
- External genitals grow
- Testes grow and produce sperm
- Shoulders and chest broaden
- Muscles develop
- Brain matures
What are the 4 hormones involved in the menstrual cycle?
- FSH (Follicle Stimulating Hormone)
- LH (Luteinising Hormone)
- Oestrogen
- Progesterone
Where is FSH secreted, and what does it do?
- Secreted by pituitary gland
- Matures eggs in ovaries
- Stimulates ovaries to produce oestrogen
Where is oestrogen secreted and what does it do?
- Secreted by ovaries
- Stimulates lining of uterus to grow after menstruation in preparation for pregnancy
- Inhibits production of FSH and stimulates LH production when oestrogen levels are high
Where is LH secreted and what does it do?
- Secreted by pituitary gland
- Stimulates the release of mature egg from ovary
- Levels of LH fall when ovulation has taken place
Where is progesterone secreted and what does it do?
- Secreted by empty egg follicle in ovary after ovulation
- Maintains uterus lining
- Inhibits FSH and LH production
- Helps maintain pregnancy if egg is fertilised
What is contraception?
Stopping sperm cells from reaching the egg cell or prevent a fertilised egg from implanting in the uterus to prevent pregnancy.
What are some contraception methods?
(Name as many as you can)
- Oral contraceptive pill
- Injections
- Patches
- Spermicide
- Condom
- Diaphragm / cap
- Intrauterine device
- Abstinence
- Male sterlisation
- Female sterilisation
What are some potential causes of infertility?
- Lack of hormones
- Damage to oviducts
- Obesity
- Eating disorders
- Age
How can women with insufficient hormones become fertile again?
Artificial FSH to mature the egg and artificial LH to trigger ovulation.
What does IVF stand for and what are the stages involved in it?
In Vitro Fertilisation
1) Giving a mother FSH to stimulate the maturation of several eggs
2) Giving a mother LH to stimulate the ovaries to the point of ovulation
3) Eggs are collected from the mother and fertilised by sperm from the father in a laboratory.
4) The fertilised eggs develop into embryos in special solutions.
5) When the eggs are tiny balls of cells, the embryos are inspected using a microscope and the healthy ones are chosen.
6) One or two of the healthy embryos are inserted into the mother’s uterus.
What is the main advantage of IVF?
Infertile women can have the chance of having a baby.
What are some disadvantages of IVF?
- Expensive for NHS and individuals
- Requires a lot of skill to carry out
- Can result in multiple births, premature births, miscarriage and stillbirths
- Not always successful, which is emotionally and physically stressful.
- Ethical issues if the mature eggs or embryos of a woman are stored for future use.
What are plant responses called?
Tropisms
What is phototropism?
When plant shoots grow towards light.
What is gravitropism?
When roots grow down towards gravity.
Which hormone controls phototropism and gravitropism?
Auxin
How does auxin distribute throughout the shoot in different light conditions and what does this mean for the shoot’s growth?
If light is equal all around the shoot, auxin distributes equally, and the shoot will grow straight up.
If light falls on one side of the shoot, auxin diffuses away from the light. This causes the cells away from the light to grow more, which makes the shoot bend towards the light.
How does auxin distribute throughout the root and what does this mean for the root’s growth?
Auxin in the root diffuses downwards, the direction of gravity, and this will slow down the growth of the side of the root with auxin. This will cause the other side to grow more, making the root bend downwards.
What do gibberellins do to plants?
- End seed dormancy.
- Speed up germination of barley seeds to make malt.
- Promote flowering throughout the year.
- Increase the size of fruits.
What does ethene do to plants?
Speeds up the ripening of fruits.
What does the thermoregulatory centre do?
Contains receptors that detect the temperature of the blood flowing through the brain. It sends impulses to the brain about skin temperature.
How would the body respond to a high body temperature?
- Vasodilation
- Sweating
- Hairs lie flat
How would the body respond to a low body temperature?
- Vasoconstriction
- Shivering
- Hairs pulled up erect
What is vasodilation and vasoconstriction?
Vasodilation
Blood vessels near the skin dilate, allowing more blood to flow there. Energy is transferred out by radiation into the environment and the skin cools.
Vasoconstriction
Blood vessels near the skin constrict, allowing less blood to flow there. Less energy is radiated into the environment.
Where and how is urea produced?
Produced in the liver through the breakdown of amino acids.
What do the kidneys do?
Controls the amount of water, mineral ions and urea that the body excretes using selective reabsorption
Which hormone controls water reabsorption in the kidneys?
ADH
What does ADH do?
A hormone that controls the amount of water that the kidney reaborbs
What is kidney dialysis?
A machine that carries out the same job as the kidneys by passing the blood between a partially permeable membrane surrounded by dialysis fluid.
What does dialysis fluid contain and how much of each?
- Glucose: same concentration as blood
- Mineral ions: same concentration as blood
- Urea: lower concentration than blood
What are the advantages and disadvantages of kidney transplants?
Advantages
- Longer lifespan than dialysis
- Patients won’t have to undergo regular dialysis
- Cheaper than dialysis
Disadvantages
- Infection risk
- Rejection risk
- Finding a donor can take a while
- Kidney lasts 8-9 years on average
- Patient must take immunosuppressant drugs to avoid rejection, but increase risk of infection.
What are the similarities and differences between sexual and asexual reproduction?
Similarities
- Both create new organisms
Differences
- Sexual reproduction involves the fusion of 2 gametes (sperm and egg) from 2 parents. Asexual reproduction involves a single organism/cell.
- Sexual reproduction has variation in offspring. Asexual reproduction produces genetically identical offspring
- Sexual reproduction takes longer, as a mate needs to be found and due to the process of mating. Asexual reproduction is faster as it doesn’t involve a mate
What is meiosis?
A form of cell division which produces 4 non-identical, haploid sex cells or gametes
What are the sex cells in:
1) Animals
2) Plants
Animals: egg cells and sperm cells
Plants: egg cells and pollen
How many times do cells divide in:
1) Mitosis
2) Meiosis
Mitosis: once
Meiosis: twice
What is a zygote?
The first cell of a new organism when an egg cell and sperm cell fuse during fertilization
What are the advantages and disadvantages of asexual reproduction?
Advantages
- Only 1 parent needed
- Quicker than sexual reproduction
- Less energy required
- Many identical offspring are created, ideal in favourable conditions
Disadvantages
- Offspring have little variation
- Environmental change affect all offspring
What are the advantages and disadvantages of sexual reproduction?
Advantages
- Produces variation, allowing natural selection
- Natural selection can be sped up by humans in selective breeding to increase food production
Disadvantages
- Two gametes are needed, usually requiring 2 parents
- Takes time and energy to find a mate or spread gametes
- Slower than asexual reproduction
How do malarial parasites reproduce:
1) In mosquitoes
2) In humans
Mosquito: sexually
Human: asexually
What is a gene?
A small section of DNA on a chromosome
What is the genome of an organism?
The entire genetic material of an organism
How does understanding the human genome help us?
- We can search for genes linked to different diseases
- We can understand and treat inherited disorders
- We can trace human migration patterns from the past
What are the 4 bases in DNA and how are they linked together?
A, C, G and T
A and T link
C and G link
What is a nucleotide?
A unit containing a sugar, a phosphate and a base.
What does amylase catalyse, where is it produced and where is it used?
- Catalyses digestion of starch into sugars
- Produced in salivary glands, pancreas and small intestine
- Used in mouth and small intestine
What does protease catalyse, where is it produced and where is it used?
- Catalyses break down proteins into amino acids
- Produced by stomach, pancreas and small intestine.
- Used in stomach and small intestine
What does lipase catalyse, where is it produced and where is it used?
- Catalyses breakdown of lipids into fatty acids and glycerol
- Produced in pancreas and small intestine
- Used by pancreas and small intestine
What are the 2 stages in protein synthesis?
- Transcription
- Translation
What is natural selection?
A process where organisms that are better adapted to the environment will survive and reproduce
What is selective breeding?
An artificial process where humans choose organisms with desired characteristics to breed, resulting in offspring having those traits
What is a community?
A group of different species that live in the same general area
What is a population?
All members of a single species that live in a habitat
What is an ecosystem?
The interaction of a community of biotic and abiotic factors elements of their environment
What is intraspecific competition?
When organisms of the same species compete with each other for resources
What is interspecific competition?
When organisms of different species compete with each other for resources
What do animals compete for?
- Food
- Water
- Mates
- Space
- Breeding sites
What do plants compete for?
- Light
- Water
- Minerals
- Space
What are some biotic factors?
(Name as many as you can)
- Availability of food
- Number of predators and prey
- New pathogens or parasites
- New competitors
What are some abiotic factors?
(Name as many as you can)
- Availability of water
- Availability of mineral ions
- Wind intensity and direction
- Availability of carbon dioxide
- Availability of oxygen
- Availability of habitats
- pH of soil
- Amount of light
- Temperature
What is an extremophile?
Organisms, usually microorganisms, that are adapted to live in conditions where most enzymes don’t work becuase they denature
(i.e. organisms that live in extreme conditions)
How are animals in colder environments adapted?
- Thick fur
- Blubber
- White camouflage for snow
- Small surface area : volume ratio
How are animals in hotter environments adapted?
- Nocturnal behaviour
- Yellow-brown fur for camoflague on sand
- Water conservation
- Large surface area : volume ratio
What is biomass?
Dry mass of material within a living organism
What is a producer?
An organism that makes its own food, usually through photosynthesis
What is a consumer?
An organism that cannot make its own food so must eat other plants and/or animals for energy
What is a decomposer?
Bacteria or fungi that break down dead plant and animal matter
Which process is the only process that removes carbon dioxide from the atmosphere?
Photosynthesis
Which organisms respire?
All organisms
Which factors affect rate of decay by decomposers?
- Temperature
- Humidity
- Oxygen availability
What is biodiversity?
The variety of living things and their interactions in a given area
What are the steps involved in water becoming polluted?
- Fertilisers and untreated sewage spills in water, causing high levels of nitrate ions
- High levels of nitrate ions causes algae and other water plants to rapidly grow
- Competition for light increases and many plants die because they cannot photosynthesise
- Microorganisms feed on dead plants so the microorganism population increases rapidly
- Respiration by microorganisms depletes oxygen concentration in water
- Aerobic organisms like fish die due to lack of oxygen, leading to even more decay
- Lack of oxygen eventually means the water cannot sustain living organisms
Why do humans carry out large-scale deforestation?
- Timber
- Land for agriculture
- Buildings
- Mining
What are the consequences of large-scale deforestation?
- Destruction of habitats, reducing biodiversity
- Climate change due to carbon dioxide store being released, and less photosynthesis
Why do humans destroy peat bogs?
- Farming
- Fuel
- Compost
How are humans working to maintain biodiversity?
- Breeding programmes
- Protection / regeneration of habitats
- Reintroduction of field margins and hedgerows
What is food security?
Having enough available, affordable, nutritious food to feed a population
Which factors affect food security?
- Environmental changes
- Pests / pathogens
- Changing diets
- Increasing birth rates
- Cost of agricultural inputs
- Conflicts / war
Why isn’t all biomass transferred to the next trophic level?
- Not all of previous level is eaten
- Not all biomass is fully digested
- Excess protein is broken down into urea
- Some biomass is used for respiration
- Some biomass is used for movement
- Some biomass is used for thermoregulation
How are animals managed so food production is more efficient?
- Limiting movement
- Controlling temperature
How are fish stocks being maintained?
- Limits on how much fishing can occur
- Large nets so small fish can escape
- Smaller fishing vessels
What is Fusarium?
A fungus that is grown to produce mycoprotein, a protein-rich food supplement for vegetarians
What are the advantages of using mycoproteins instead of meat?
- Fungi use cheap food
- Fungi reproduce rapidly
- Suitable for vegetarians
- No need to farm and slaughter animals
- Low in fat
What is aseptic technique?
A set of practices used to prevent contamination when working with microorganisms
How often do bacteria multiply?
Around every 20 minutes
How should you decontaminate before a bacterial growth practical?
- Wipe down surfaces
- Use clean pipettes
- Rinse glassware beforehand
- Inoculating loop through a flame
- Wash hands
What are the stages involved during transcription in protein synthesis?
1) DNA unwinds and 2 strands seperate
2) Nucleotides in the nucleus line up next to a strand, using complementary base pairings
3) The nucleotide and strand are bonded together, forming a template molecule
4) The template molecule detaches and leaves the nucleus
5) The 2 DNA strands come back together and the double-helix winds back up
What are the stages involved during translation in protein synthesis?
1) Template molecules attaches to a ribosome
2) A carrier molecule binds to the template using complementary base pairing to attach to the first triplet
3) The next carrier arrives, with a complementary base sequence to the next triplet
4) A bond is formed between the 2 amino acids
5) The first carrier leaves and a third carrier binds to the third triplet
This continues until all amino acids are in place
What is the inverse square law?
Light intensity = 1 / distance²
Intensity of light is inversely proportional to the square of the distance from the light source
(This is important for the photosynthesis required practical)
What are the levels of organisation? Order from smallest to largest
- Cells
- Tissues
- Organs
- Organ systems
- Organisms
What does the gall bladder do?
Stores and releases bile
What are new drugs trailled for?
- Toxicity: are they harmful?
- Efficacy: does it work?
- Dose: what amount is safe and effective?
How does a healthy kidney produce urine?
- Filtering blood
- Reabsorbing all glucose
- Reabsorbing mineral ions the body needs
- Reabsorbing water the body needs
- Releasing urea, excess mineral ions and water in the urine
