Biology🌱 Flashcards
Animal Cells
Cytoplasm Nucleus Ribosomes Mitochondria Cell membrane
Plant Cells
Cytoplasm Nucleus Ribosomes Vacuole Mitochondria Cell membrane Cell wall Chloroplast
Use of Cell Membrane
Semi-permeable structure that allows some substances to pass through but not all. Therefore it controls movement of substances in and out of the cell.
Use of Cytoplasm
A jelly-like material that contains dissolved nutrients and salts. This is where chemical reactions occur.
Use of Nucleus
Contains genetic material, including DNA and controls cell activities.
Use of Mitochondria
Contains enzymes for respiration and is where most energy is released for respiration.
Use of Cell Wall
Made for cellulose fibres and strengths and supports the cell.
Use of Chloroplast
Contains chlorophyll (green pigment) which absorbs light energy for photosynthesis. Contains enzymes needed for photosynthesis.
Use of Vacuole
Filled with cell sap to help keep the cell turgid.
Prokaryotic Cells
A cell without a nucleus e.g. bacteria and archaea.
Use of Chromosomal DNA
The DNA of bacterial cells is found loose in cytoplasm.
 Use of Plasmid DNA
Small, closed-circles of DNA present in the cytoplasm. Unlike chromosomal DNA, plasmid DNA can move from one bacterium to another giving variation.
Levels of Organisation
Subatomic particles, atoms, molecules, organelles, cells, tissues, organs, organ systems, organisms and biosphere (figure).
Process of Diffusion
Movement of a substance from a high concentration to a low concentration.
Process of Osmosis
Movement of water through a semi-permeable membrane from a high concentration to a low concentration.
Process of Active Transport
Requires energy to move substances from a low concentration to a high concentration. It goes against the concentration gradient.
Mitosis Conditions
2 daughter cells 1 stage cell division Diploid (46 chromosomes) Genetically identical Body cells (not eggs or sperm) Prophase is shorter
What does Uncontrolled cell growth lead to?
Cancer
Meiosis Conditions
4 daughter cells 2 stage cell division Genetically different Only occurs in animals, plants and fungi Creates germ cells (eggs and sperm) Haploid (23 Chromosomes) Prophase is longer
Asexual Reproduction Conditions
One parent
Offspring are genetically identical
Sexual Reproduction Conditions
2 Parent cells
Offspring are genetically different leading to variation
XX Chromosomes
Females
XY Chromosomes
Males
Gene Definition
Small section of DNA on a chromosome that codes for a particular sequence of amino acid, to make a certain protein.
Allele Definition
Variant form of a gene (Different version of the same gene).
Dominant Definition
Expressed with a capital letter.
Recessive Definition
Expressed with a lowercase letter.
Heterozygous Definition
Someone with different alleles for a specific gene.
Homozygous Definition
Someone with identical alleles for a specific gene.
Phenotype Definition
The particular version of a characteristic seen in an individual.
Genotype Definition
The collection of alleles that determine an organism’s characteristic.
Chromosome Definition
Thin strand of DNA.
What is a Genome?
The entire genetic material (DNA) of an organism
What do Chromosomes contain?
DNA
What is DNA?
A polymer made up of two strands forming a double helix
How many nucleotides make up DNA?
4
Complimentary Bases
(A) Adenine
(T) Thymine
(C) Cytosine
(G) Guanine
What does Adenine bind with?
Thymine
What does Cytosine bind with?
Guanine
What do Genes carry?
Codes for proteins
How is the genetic code read?
In triplets
What does each triplet code for?
Amino Acid
What does protein synthesis involve?
The production of proteins from amino acids
What is a mutation?
A change in DNA
Genetic engineering process
1) Selection of desired characteristic
2) Isolation of the gene responsible for this characteristic
3) Insertion of the gene into another organism
4) Replication of the transgenic organism
Example of genetic engineering in different types of cells
Bacteria cells making insulin
Crops
Golden rice (produces beta carotene)
Benefits and risks of genetic engineering in medical application
Faster and more efficient
Improves quality
Plants can produce toxins to discourage insects from eating
!
Belief that it is not ethical to interfere in natures way
GM crops could be harmful (toxins have been detected in blood)
GM crops could cause allergic reactions in people
What are embryonic stem cells?
Cells that can differentiate into any cell around the body. It loses this ability has the cell matures.
Functions of Stem cells
To divide and develop into any specialised body cell. They serve as a repair system for the body.
Benefits and risks of using stem cells in medical applications
Treating patients with currently untreatable conditions
Growing organs for transplant
Medical research
!
Clinical issue (can mutate and cause cancer)
Ethical issue (what stage is the embryo treated as a human?)
Social issue (expensive treatment and can cause false hope)
Impact of selective breeding on domesticated animals
Find answer
Is there genetic variation within a population of species
Yes, there is usually an extensive genetic variation within a population of species
What is evolution?
A change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species.
How does evolution occur through natural selection?
When certain genotypes produce more offspring than other genotypes in response to the environment.
Antibiotic Resistance
When germs like bacteria and fungi develop the ability to defeat the drugs designed to kill them.
If variation can be genetic/inherited, what does that result in?
In a range of phenotypes
If variation is environmental, what does that result in?
As variation can also be environmental, it affects a range of phenotypes
What are enzymes?
Biological catalysts
Mechanism of enzyme action
1) Substrate bides to the active site of the enzyme
2) Enzyme catalyses breakdown to the substrate
3) Products are released from active site
How does temperature affect the rate of enzyme action?
As the temperature increases, the rate increases.
If the temperature is too high, the enzyme will denature.
The optimum temperature is when the most products are created.
How does pH affect the rate of enzyme action?
As you increase the pH, rate of reaction increases.
If the pH is too strong, enzyme activity decreases as the active site begins to deform.
The optimum pH is when the enzyme works best.
Role of amylase in digestion
Breaking down carbohydrates.
Role of protease in digestion
Breaking down proteins.
Role of lipase in digestion
Breaking down fats and lipids.
Process of Cellular Respiration
When organisms respire in order to release energy to fuel their living processes. This process is exothermic.
Process of Aerobic Respiration
Respiration that uses oxygen to break down food molecules.
Aerobic Respiration equation
Glucose + Water = Carbon dioxide + Water
(+ ATP)
What does the central nervous system comprise?
The brain and spinal cord
Structure and function of sensory neurons
Carries nerve impulses from sensory receptors towards the central nervous system and brain.
Structure and function of relay neurons
Allows sensory and motor neutrons to communicate with each other.
Structure and function of motor neurons
Controls all of our muscle movement.
Structure and function of synapses
Allows a signal to pass from one neuron to the next.
Structure and function of the reflex arc
Receptor in the skin that detects a stimulus (change in temperature etc).
Structure and function of respiratory system
Network of organs and tissues that help you breathe. Includes your airways, lungs and blood vessels.
Structure of the thorax
Part of the body between the neck and abdomen.
Process of ventilation and gas exchange
Ventilation, or breathing, is the movement of air through the conducting passages between the atmosphere and the lungs. Gas exchange is the process of absorbing inhaled atmospheric oxygen molecules into the bloodstream and offloading carbon dioxide from the bloodstream into the atmosphere.
The importance of a high surface area : volume ratio for the gas exchange process.
Find answer
Structure and function of circulatory system
The circulatory system is made up of blood vessels that carry blood away from and towards the heart.
Structure and function of the heart
The heart is a large muscular pump and is divided into two halves. Right-side is deoxygenated blood to the lungs. Left-side is oxygenated blood around the body.
Heart rate and ECGs
Heart rate is the speed at which the heart beats. An electrocardiogram (ECG) is a simple test that can be used to check your heart’s rhythm and electrical activity.
Arteries Definition
Carry blood away from the heart.
Vein Definition
Carry blood to the heart.
Capillary Definition
Where gas exchange takes place.
What do red blood cells do?
Carry oxygen
What do white blood cells do?
Involved in antibody production and phagocytosis
What do platelets do?
Involved in blood clotting
What does plasma do?
Involved in the transport of blood components and other dissolved substances including hormones, antibodies, urea and carbon dioxide, and in the distribution of heat.
Structure and function of digestive system
Digestion is the breakdown of carbohydrates, proteins and fats into small soluble substances to be absorbed into the blood. Amylase, proteases and lipases are enzymes that are important in digestion.
Process of peristalsis
Peristalsis is a series of wave-like muscle contractions that move food through the digestive tract.
Process of digestion
1) Chemical Digestion starts in the mouth through enzymes and saliva. Food goes to the stomach.
2) The Small Intestine gets the food and produces enzymes, food is absorbed into blood, large surface area by villi.
3) Large Intestine (Colon) is where indigestible food is passed to. Any excess water is absorbed before it is excreted from the anus.
Process of absorption
The movement of digested food molecules through the wall of the intestine into the blood or lymph.
Process of egestion
The process of passing out the remains of food that has not been digested, as faeces, through the anus.
Structure and function of the excretory system
The Excretory system is responsible for the elimination of wastes produced by homeostasis.
Structure and function of the kidney
The kidney regulates/controls the water and salt content and removes urea. The kidneys filter the blood to remove waste products, which they convert into urine.
Structure and function of the nephron
Microscopic structure where urine is produced.
Role of kidneys in homeostasis
The kidneys control the amount of water, ions, and other substances in the blood by excreting more or less of them in urine.
What is homeostasis?
The maintenance of a constant internal environment
Concept of negative feedback
Responds when conditions change from the ideal or set point and returns conditions to this set point.
Regulation of blood glucose levels
Find answer
Role of insulin
Insulin is a hormone your pancreas makes to lower blood glucose, or sugar.
Role of glucagon
Glucagon raises your blood glucose level once again.
Type 1 diabetes
Type 1 diabetes is a disorder in which the pancreas fails to produce enough insulin. This can be detected from an early age.
Type 2 diabetes
In type 2 diabetes the person’s body cells no longer respond to insulin produced by the pancreas.
How can type 1 diabetes be treated?
It can be treated by injecting insulin.
Regulation of water content
The water content of the blood is controlled by a hormone called anti-diuretic hormone (ADH).
What is ADH?
Anti-diuretic Hormone. Different amounts of ADH are released into the bloodstream according to the concentration of the blood plasma.
The regulation of temperature
When we get too hot, we sweat. Sweat is released onto the surface of the epidermis. The sweat evaporates, transferring heat energy from the skin to the environment.
When we get too cold, are skeletal muscles contact rapidly causing a shiver. Nerved impulses are sent to our body hair becomes erect and stand up.
Pituitary Gland
The ‘master gland’, situated at the base of the brain
Thyroid Gland
Produces thyroxine
Pancreas
Produces insulin
Adrenal Gland
Produces adrenaline
Testes
Produces testosterone
Ovaries
Produces oestrogen
Roles of thyroxine in the body
Thyroxine plays an important role in growth and development. Regulate the rate at which calories are burned, affecting weight loss or weight gain.
Role of adrenaline in the body
Increasing the heart rate Increasing blood pressure Expanding the air passages of the lungs Enlarging the pupil in the eye Redistributing blood to the muscles
Examples of negative feedback
Thermoregulation
Blood sugar regulation
Osmoregulation
The role of hormones in human reproduction
They help develop and maintain female sex characteristics and play an important role in the menstrual cycle, fertility, and pregnancy. Male reproductive hormones, such as testosterone, help develop and maintain male sex characteristics and help make sperm in the testes.
Hormonal forms of contraception
An implant, injections, birth control pills, vaginal rings, and skin patches.
Non-hormonal forms of contraception
Condoms, Waiting for days your not ovulating, spermicide, abstinence.
What are communicable diseases caused by?
Pathogenic bacteria
Viruses
Protists
Fungi
Transmission routes of STIs
Many STIs are spread through contact with infected body fluids such as blood, vaginal fluids, or semen.
The effect on the immune system of HIV which results in AIDS
The reduction in the number of T lymphocytes in the body due to HIV can then lead to the development of Acquired Immune Deficiency Syndrome (AIDS).
Weaker immune system
More vulnerable to infections
No cure
The use of antibiotics
Antibiotics are used to treat or prevent some types of bacterial infections. Ineffective against viral infections such as the flu or cold.
The use of vaccines
Vaccines teach your immune system how to create antibodies that protect you from diseases. Your memory cells then remember how to fight the disease.
Prevent spread of STIs
Wearing a condom
Get checked regularly
Wash before and after intercourse
Preventing spread of HIV
Tell your sexual partners if you have HIV
Use a clean needle
Wear a condom
HIV prevention medicines such as pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP).
How was penicillin discovered?
New drugs are being developed all the time. One of the most famous discoveries was made by Sir Alexander Fleming, who discovered penicillin from the Penicillin mould.
Preclinical testing
1) The drug is tested on cells in the lab
2) Computer models may also be used to simulate the metabolic pathways that may be taken by the drug
3) Efficacy and toxicity are tested at this stage
Clinical Testing
1) The drug is tested on human volunteers first, generally with a very low dose then increased. 2)Low dose so that it is safe.
3) Tested on patients with condition next.
4) The patients are often split into two groups; one given the drug the other given a placebo. 5)This is called a double-blind study – neither the doctor nor the patient knows if the patient is getting the placebo or the active drug
6) Once the drug is found to be safe then the lowest effective dose is tested at this stage
What diseases are caused by the interaction of many factors?
Cardiovascular disease, Many forms of Cancer, some Lung and Liver diseases and diseases influenced by nutrition, including type 2 diabetes.
How can cardiovascular disease be treated?
Cardiovascular disease can be treated/managed using life-long
medication (including statins, anti-coagulants and anti-hypertensive drugs),
surgical procedures (including stents and bypass for coronary heart
disease), and lifestyle changes (including reducing smoking, more exercise
and a balanced diet)
Different levels of organisation in an ecosystem
Individual organisms, Populations, Communities, Whole ecosystem.
Biotic Factors
(living components of an ecosytem)
Humans, insects, wild animals, birds, bacteria, etc.
Abiotic Factors
(physical or chemical changes in the environment)
Soil, rainfall, humidity, temperature, pH, climate, etc.
Factors that cause a change in population size
Births
Deaths
Migration
The importance of interdependence in ecosystems (relating to
predation, mutualism and parasitism) and of competition in a community
Interpendence
Organisms in an ecosystem rely on each other for their survival
Parasite
An organism that lives in or on another organism (the host).
Mutualism
Both species benefit from the arrangement.
Name the primary producers
Photosynthetic organisms are the primary producers of food in an ecosystem, and therefore biomass.
Importance of the carbon cycle
Importance of photosynthesis in the carbon cycle
Plants absorb carbon dioxide from the atmosphere and form it into sugar, starch and other organic compounds. Only process which decreases CO2 levels.
Importance of respiration in the carbon cycle
Adds CO2 into the environment, plants then convert CO2 into O2.
Importance of combustion in the carbon cycle
By-product of combustion is that it releases carbon dioxide back into the atmosphere.
Importance of decomposition in the carbon cycle
Decomposition of organic matter (i.e. dead plant and animal remains) in soils is an important process in any ecosystem. Recycles carbon back into the atmosphere.
The importance of the water cycle to living organisms
It enables the availability of water for all living organisms and regulates weather patterns on our planet.
