Cells and Microscopy Flashcards
What functional adaptations does a sperm cell have?
- Acrosome at the front of the head which stores enzymes required to break down the cell membrane oof the egg cell
- Haploid nucleus to fuse with the egg cell
- long tail to efficiently swim to the egg
- lots of mitochondria to supply the energy needed to swim to the egg.
What functional adaptations does an egg cell have?
- extra nutrients in the cytoplasm to feed the embryo
- haploid nucleus to fuse with the sperm cell
- cell membrane which changes after fertilization
What is the main function of the sperm cell?
Transport male DNA to the female DNA in the egg.
What is the main function of the egg cell?
Carry female DNA and nourish the developing embryos in the early stages.
What does Haploid mean?
Half the number of chromosomes in the normal cell
What is the main function of a ciliated epithelial cell?
Move substances - the cilia beat to move the substances in one direction, along the surface of the tissue
What is the main function of epithelial cells?
line the surfaces of organs
How to prepare a microscope slide (light microscope)
- place a drop of water on slide
- place specimen into water drop
- Add a drop of iodine to stain for sub-cellular structures
How to observe an image through a light microscope
- Clip the slide into place
- Select the lowest magnification lens
- Use the course adjustment knob to move the stage just below the objective lens
- look down the eye piece and use the course adjustment to move the image into focus
- Adjust focus with fine adjustment knob
- change magnification lens if required and refocus.
Drawing the cell from a microscope image
- Always use a sharp pencil with clear, unbroken lines.
- Drawings should not include color or shade.
- Subcellular structures should be drawn in proportion
- Include a title of what is being drawn
- Label the features using straight, uncrossed lines
If you know the power of your lenses, how do you calculate magnification?
Total magnification = eyepiece lens magnification x objective lens magnification
If you don’t know the power of your lenses, how do you calculate magnification?
magnification = image size / real size
What color is iodine in the presence of starch?
blue-black
What color is iodine without ht presence of starch?
orangey-brown
Equation for rate of reaction:
Rate (s-1) = 1000/time
What does a carbohydrase do?
Convert carbohydrates into simple sugars
Equation for change of reaction over time:
Rate = change/time
Give an example of a carbohydrase
Amylase
What does Amylase do?
Breaks down starch into maltose
What do protease enzymes do?
Protease enzymes catalyse the conversion of proteins into amino acids
What do lipases do?
Catalyse the conversation of lipids not glycerol and fatty acids
What does glycogen synthase do?
Joins together chains of glucose to make glycogen
How do you test for reducing sugars?
Benedicts test
What color changes would you observe using the Benedicts test?
Blue-is –> green –> yellow –> red
The higher the concentration of reducing sugar the further the color change goes (red = high)
How do you test for starch?
Iodine
How do you test for proteins?
biuret test
How does the biuret test work?
Add a few drops of copper(II) sulfate to an alkane solution (potassium hydroxide). The copper(II) sulfate solution is a bright blue If the food sample contains protein the solution will change from blue to pink or purple. If no protein is present, the solution will stay bright blue.
How do you test for lipids?
The emulsion test
How do you perform the emulsion test?
Add a food sample to 2cm^3 ethanol
Shake the tube for about 1 minute
pour the solution into another tube containing distilled water
If any lipids are present they will precipitate out of solution and appear like a milky emulsion.
What is calorimetry?
The test used to quantify the energy stored in food
How do you perform a calorimetry test?
- Add the food on to the end of a skewer.
- Add water to a boiling test tube held in place by a clamp
- Set fire to the food and hold it underneath the tube
- Repeatedly set fire to the food until it won’t catch light any more
- measure the increase in temperature of the water in the tube
Formula for working out calorimetry test
- energy in food (j) = mass of water (g) x temp change of water (^C) x 4.2.
- energy per gram of food (J/g) = energy in food (J)/mass of food (g)
What is the specific heat capacity of water?
4.2
What does specific heat capacity mean?
The number of joules required to raise the temp of 1g of water by 1^C
1cm^3 is the same as how many grams?
1g
What is diffusion?
The spreading of particles from an area of high concentration to low concentration
Is diffusion passive or active transport?
Passive
How permeable are cell membranes?
Partially permeable
What is osmosis?
The net movement of water molecules across a partially permeable membrane from a region of high water concentration to low water concentration
Name two types of passive transport
Osmosis and diffusion
What is active transport?
When particles are moved up a concentration gradient using energy
Give an example of active transport
Digestive system:
Active transport allows nutrients to be taken into the blood from the gut, despite the fact that the concentration gradient is the wrong way.
What is a dependent variable?
The variable being tested
The independent variable
The variable that is changed or controlled
Equation for finding the % change
(Final mass - initial mass)
/ initial mass
X 100
What does isotonic mean?
When the concentration of fluids between an osmotic membrane is the same
What does diploid mean?
Two copies of chromosomes per cell
What are chromosomes?
Long lengths of DNA
What is mitosis?
When a cell reproduces itself by splitting in two to form two genetically identical offspring.
What is cytokinesis?
The division of the cytoplasm
What happens during interphase?
The cell grows and increases the number of sub cellular structures such as ribosomes, mitochondria etc.
DNA is duplicated so that there is one copy of each chromosome for each cell.
Each arm of a chromosome is called…
a Chromatid
Four stages of mitosis:
in order
- prophase
- metaphase
- anaphase
- telophase
What is the process of the cytoplasm dividing?
Cytokinesis
What happens in prophase?
The chromosomes condense, getting shorter and fatter.
The membrane around the nucleus breaks down and the chromosomes lie free in the cytoplasm.
What happens in Metaphase?
The chromosomes line up at the centre of the cell
What happens in Anaphase?
Spindle fibres pull the chromosomes apart.
The two chromatids are pull towards opposite ends of the cell.
What happens in telophase?
Membranes form around each of the sets of chromosomes. These become the nuclei of the two new cells - the nucleus has divided.
Uses for mitosis:
- For multicellular organisms to grow
- To replace cells that have been damaged
- By some organisms to reproduce by asexual reproduction
Which two processes do cells use to grow and develop?
- Cell division
2. Differentiation
What is cell differentiation?
The process by which a cell changes to become specialized for its job.
Why is differentiation necessary?
It allows multicellular organisms to work more efficiently because different cell types can carry out different functions
Plant cells have an additional property they use to grow, what is it?
Cell elongation.
All growth in animals happens by which process?
Cell division
Which process do plant cells use to grow?
Cell division and cell elongation
Describe growth in plants
In plants, growth in height is mostly due to cell elongation.
Cell division happens at the tips of the roots and shoots, in areas called meristems.
Plants and trees use differentiation to to develop new branches with leaves, or roots.
What is a tumor?
A mass of abnormal cells
What is a stem cell?
An undifferentiated cell
Where would you find a stem cell in an adult human?
Bone marrow
Give an example of a disease which might be treated with a bone marrow transplant
sickle cell anaemia
What are the considerations for using stem cells in medicine? (4)
- tumor development - stem cells divide quickly, if this can’t be controlled cancer could form
- Disease transmission - viruses live inside cells and this could be transmitted from donor to recipient
- Rejection - If the transplanted cells aren’t grown using the patient’s own stem cells, the patient’s body may recognize them as foreign and trigger the immune system to fight and kill them. Drugs are available to suppress the immune response but this then makes the patient susceptible to other diseases
- Ethics of using stem cells - Because they are cells from fertilized embryos, campaigners think that stem cells are unethical since each one is a potential human life.
In plants, where do you find undifferentiated diving cells?
Meristems
This found in the regions of the plants which are used fro growing… i.e. the tips of the roots and shoots.
What are sensory receptors?
A group of cells that detect stimuli and initiate responses to them. Different receptors detect different stimuli.
Examples of sensory receptors
- in the eye to detect light
- in the skin to detect touch, tissue damage to temperature change
Where is all the sensory information sent?
the Central Nervous System (CNS)
What is the purpose of the CNS?
Where information from the sensory receptors is sent and where reflexes and action are are coordinated
What comprises the CNS?
in vertebrates, the Brain and spine
Three types of neurons?
- sensory
- motor
- Relay
What is an effector?
Instructions are sent from the CNS, along the neurons and to the effectors. Effectors are muscles or glands which respond to the information to bring about a response, e.g. movement or release of hormone.
What does a Sensory neuron do?
Carry information as electrical impulses from the sensory receptor to the CNS
What does a motor neuron do?
Carries electrical impulses from the CNS to the effector
What does a Relay neuron do?
Carries electrical impulses from the sensory neurons to the motor neurons.
They are found in the CNS.
From stimulus to effector, what is the order in which each type of neuron is used?
- Sensory (Sensory to relay in CNS)
- Relay (found in CNS, receives info from sensory neurons and relays it back to motor neurons)
- motor neurons (receives info from relay neurons in the CNS and carries it to the effectors)
What functional specific structure does a neuronal cell have?
dendrites and deuterons carry nerve impulses towards the cell body
axons carry nerve impulses away from the cell body
Some axons are surrounded by myelin sheath
What is myelin sheath?
A fatty layer that acts as an electrical insulator, speeding up the electrical impulse
Can be found surrounding some axons
Structure of a sensory neuron
One long dendron that carries nerve impulses from the receptor cells and to the cell body, which is located in the middle of the neuron.
One short axon carries nerve impulses from the cell body to the CNS
Structure of a motor neuron
Many short dendrites which carry nerve impulses from the CNS to the cell body
One long axon carries nerve impulses from the cell body to effector cells
Structure of a relay neuron
Many short dendrites which carry nerve impulses from sensory neurons to the cell body
One axon which carries nerve impulses from the cell body to morrow neurons.
What is the connection between two neurons called?
Synapse
What is a synapse?
the connection between two neurons
How is the nerve signal transmitted between two neurons?
Via neurotransmitters
How do neurotransmitters move across the synapse?
diffusion
What is a reflex?
Fast automatic responses which bypass the conscious brain when a quick response is essential.
What is the passage of information in a reflex called?
Reflex arc
The Reflex arc stages are:
- stimulus detects by receptors and impluses are sent along a sensory neuron a relay neuron in the CNS
- The impulse sent down the sensory neuron towards the relay neuron and neurotransmitters are released at the synapse. The impulse is then sent along the relay neuron.
- When the impulse reaches the synapse between the relay neuron and the motor neuron, neurotransmitters are released towards the motor neuron. this cause impulses to be sent down the motor neuron.
- impulses ent down the motor neuron to effector (usually a muscle)
- if the effector is a muscle, it will respond to the impulse by contracting. Or if it’s a gland, it’ll secrete a hormone.
Regions of the brain
- cerebrum (divides into two halves)
- Cerebellum
- medulla oblongata
What does the cerebrum do?
The large part of the brain
split into two hemispheres - left and right.
The right side controls muscles no the left side of the body and vice versa.
Involved in control f movement, intelligence, memory, language and vision.
Where do you find the cerebellum and what does do?
Found at the back of the brain
Responsible for muscle coordination and balance.
Where do you find the medulla oblongata and what does it do?
Found at the base of the brain, at the top of the spinal chord
It control unconscious activities like breathing and your heart rate
Types of scanners used for imaging the brain
- CT
2. PET
How does a CT scanner work and what will it show?
Uses X-rays to produce and image of the brain
Can show the main structures of the brain, but doesn’t show their functions
How does a PET scan work and what is it good at identifying?
A radioactive chemical (called a “tracer”) is injected into the patient. The radioactive chemical moves round the body and collects in different places, including the brain. More active cells take up more tracer than less active cells. The patient then lies in the PET scanner and an image can be created based on which cells are active and which aren’t.
PET scanners can create very detailed images to investigate the function and structure of the brain.
Usually used to identify which areas of the brain are active or inactive when investigating disorders that change the brains activity.
Why is it difficult to treat nervous system?
- It’s hard to repair damage too the nervous system - these cells don’t repair themselves and scientists haven’t work out how to do it outside of the body either.
- It’s difficult to access the nervous system, and some regions is impossible to reach without causes permanent damage.
Structure of the eye:
- Cornea
- Lens
- Pupil
- Irs
- Retina
- Ciliary muscles and suspensory ligaments
- Optic Nerve
What is the cornea and what does it do?
- The transparent outer layer found at the front of the eye
- Refracts light
What does the lens do and where do you find it?
- Refracts light, focussing it onto the retina
- Found behind the pupil
What does the pupil do?
hole at the centre of the eye that light enters through.
What is the iris and what does it do?
Contains muscles that allow it to control the diameter of the pupil and therefore how much light enters the eye
What is the retina and what does it do?
the layer at the back of the eye that contains two types of light receptor cells - rods and cones.
Rods are sensitive to light intensity and cones are sensitive to color.
What do the Ciliary muscles and suspensory ligaments doo?
control the shape of the lens
What does the optic nerve do?
The information from light is converted into electrical impulses by the rods and cones on the retina. The optic nerve carries impulse from these receptors to the brain. It’s a sensory neuron.
When referring to the eye, what is meant by accommodation?
When the eye focuses light on the retina by changing the shape of the elastic lens.
This is reflex used when observing the near or far.
What is the process of focussing on the near object?
- ciliary muscles contract
- lens becomes more rounded
This increases the amount by which it refracts light.
What is the process of focussing on the distant object?
- Ciliary muscles relax, this allows the suspensory ligaments to contract
- the lens is pulled into to a less rounded, thinner shape
Less refraction of light
What happens to the eye when an individual is long-sighted?
The lens is the wrong shape and doesn’t refract light enough, or the eyeball is too short.
This can be remedies with convex glasses
What happens to the eye when an individual is short-sighted?
The lens is the wrong shape and refracts the light too much or the eye ball is too long.
Images of the object are brought into focus in front of the retina
This can be remedied using concave glasses or contact lenses
Whats the most comment type of color-blindness?
Red-green
What causes color blindness?
When the color cones in the retina are not working properly
What is a cataract?
A cloudy patch on the lens which stops light from being able yo enter the eye normally
What is the implication of a cataract for the individual?
blurred vision, less vivid color detection and difficulty seeing in bright light
It can be treated surgically by replacing the faulty lens with an artificial one.
What is sexual reproduction?
Where genetic information from two organisms is combined to produce offspring which are genetically different to either parent.
-involves gamates
What are gametes?
- Reproductive cells, i..e. sperm cells or egg cells.
- Haploid
In flowering plants which is the male and females gametes?
male gametes are the pollen, while female is the ovules
What is a zygote
the combined male and female gametes
-e.g. the fertilized egg.
What is meiosis?
A type fo cell division but its different from mitosis because:
- it doesn’t produce identical cells
- it produces cells with half the number of chromosomes
- only takes place in the reproductive organs
Cell division by meiosis:
- Before the cell starts to divide, it duplicates its genetic information, forming two armed chromosomes - one arm is an exact replica of the other. After replication, the chromosomes arrange themselves into pairs.
- In the first division in meiosis, the chromosome pairs line up in the center of the cell.
- The pairs are then pulled apart so that each new cell only has one copy
- Second division - Chromosomes line up in the centre of the cell and the arms of the chromosomes are pulled apart.
- There are four haploid daughter cells - gamete cells.. There is only a single set of chromosomes in each and they are all genetically different from one another.
Advantages of asexual reproduction
- Can produce lots of offspring quickly
2. Organisms can reproduce whenever conditions are favorable, without having to wait for a mate.
Examples of asexual reproduction:
Dandelion plants
Sea Sparkle
Banana plants
Disadvantages of asexual reproduction
No genetic variation between offspring so if the environment changes and the conditions become unfavorable, the whole population will die out.
Advantages of sexual reproduction
Have a mixture of two sets of chromosomes creating genetic variation
Variation increases the changes of a species surviving changing environments because they have a survival advantage.
Disadvantages of sexual reproduction
Organisms need to find a mate to reproduce with, this means that it takes more times and energy.
Fewer offspring will be produced in a life span.
What is DNA
A polymer of nucleotides put together in a long chain
-found in the nucleus of eukaryotes
What is a chromosome
two strands of DNA twisted together in a double helix
What is a gene?
A small section of DNA
-It codes for a particular sequence of amino acids which are added together to make a protein
What is the genome?
The whole of an organisms DNA
What makes a nucleotide?
Base, sugar backbone and phosphate group
- The base is always attached to the sugar
- sugar always attached to the phosphate
What is the sugar-phosphate backbone?
Sugar and phosphate group
Which pairs always link together?
A –> T
G –> C
-and vice versa
-linked together with weak hydrogen bonds
How would you extract DNA from fruit?
- Mix fruit with detergent and salt
- Detergents breaks down the the cell membrane to release DNA
- Salt makes DNA stick together - filter the mixture t get the insoluble bits out
- gently add ice-cold ethanol to the filtered mixture
- DNA will precipitate out of solution because it is not soluble in cold alcohol. - should appear as white, sticky mass.
Proteins are
polymers of amino acids
What is the base triplet?
The three DNA bases that code for an amino acid
What is a triplet code?
A code based on base triplets
What does non-coding mean
The region doesn’t code for amino acids
They control whether a gene is expressed.
What is a genetic mutation or variant?
A random change to a base in the DNA sequence
-This may or may not result in a changed amino acid
What are the two stages of protein synthesis?
Transcription (nucleus) and translation (cytoplasm)
What are ribosome?
Involved in joining amino acids together during translation
What is transcription?
When DNA is copied into single stranded mRNA to be transported from the nucleus to the ribosome in the cytoplasm. - completed by RNA polymerase.
How does transcription work?
- RNA polymerase binds to the region of non-coding DNA in front of the gene.
- The two DNA strands unzip and the RNA polymerase moves along one of the strands of DNA, producing an mRNA molecule that complements the sequence of the gene.Base pairing between the DNA and RNA ensures the mRNA is complementary to the gene.
- The mRNA molecular moves out of the nucleus and joins up with a ribosome in the cytoplasm.
How does transcription work?
- mRNA is bound to the ribosome
- The amino acids are brought to the ribosome by another molecule called tRNA
- Amino acids are joined in a sequence the directly matches the sequence of the mRNA codons.
- When anti-codon of the tRNA matches the codon of the mRNA, the ribosome joins the amino acids in a polypeptide chain. The empty tRNA then moves away again.
What is a phenotype?
An organisms characteristics
How do mutations in non-coding regions effect proteins?
Chaning of the regulatory regions and how proteins such as RNA polymerase bind. Implications of having too much or too little mRNA, and therefore protein, is produced.
What is an allele?
Genes that are on different chromosomes
What does heterozygous mean?
Alleles are different
What does homozygous mean?
The alleles code the same.
What is the dominant allele?
The allele whose traits are shown phenotypically
What is the recessive allele?
The allele whose traits are not shown phenotypically
What is genotype?
The combination of alleles you have.
What is a monohybrid cross?
Genetically crossing two parents to look at just one characteristic
Sex chromosomes of men
XY
Sex chromosomes oof women
XX
Which sex chromosomes do Sperm carry?
either X or Y
Which sex chromosomes so eggs carry?
X
What determines the sex of an embryo?
Whether it carries an X or a Y chromosome
What are the two types of variation?
Genetic variation
Environmental variation
Which is the recessive blood-type allele?
blood type O
Environmental variation is also known as acquired characteristics, what does it mean?
Characteristics that an organism acquires during their lifespan.
What is evolution?
The slow and continuous change if an organisms’ inherited characteristics from one generation to the next.
What is Natural Selection?
When variation in alleles causes a selective advantage over different selection pressures, those variation with advances will survive, those without will die out.
Evidence for evolution can be found in…
Antibiotic resistance
Fossils
Human beings and our evolutionary ancestors are known as…
hominids
In human evolution, who is Ardi?
A hominid fossil of the species Ardipithecus ramidus
She was found in Ethiopia and is 4.4 million years old.
What about Ardi’s features suggest she is a mixture of human and ape?
- The structure of her feet suggests she climbed tortes - an ape-like big toe two grasp branches
- Long arms and Short legs
- Brain was about the same size as a chimpanzee
- The structure of her legs suggests she walked upright.
- Bone structure in her hands suggests she didn’t use her hand to help her walk
What is cranial capacity?
It’s the space taken up by the brain in the skull, thoughts to be the brain size.
In human evolution, who is Lucy?
A hominid fossil of the species Australopithecus afarensis. She was found in Ethiopia and is thought to be 3.2 million years old.
She is more human-like that Ardi
What about Lucy’s features make her more human-like than Ardi?
- Arched feet, more adapted to walking than climbing, and no ape-like big toe
- The size of her arms and legs was in the middle of the expected size for apes and humans
- Her brain was larger than Ardi’s but still smaller in size to a chimp’s brain.
- Structure of her leg and feet bones suggest she walked upright, more efficiently than Ardi.
Who is Turkana Boy?
A 1.6 million year old fossil found in Kenya
From species Homo Erectus
More human-like than Lucy
Features Turkana boy?
Shortt arms and long legs are much more human than an ape
Brain was much larger than Lucy’s - similar to human size
Structure of his legs and feet suggests he was even better adapted tot walking upright than Lucy.
Fossils by age, starting with the oldest -
Ardi
Lucy
Turkana boy
How can you use the development of tools as evidence of human evolution?
They started using stone tools and these gradually became more complex, so their brains must have been getting larger.
Who are homo Habilis and whaat tools did they use?
Lived between 2.5-1.5 million years ago
They made simple stone tools called pebble tools by hitting rocks together to make sharp flakes. These could be used to scrape meat from bones or crack bones open
Who are Homo Erectus and what tools did they use?
Lived between 2 - 0.3 million years ago
Sculpted rocks into shapes to produce more complex tools like simple hand-axes. These could be used to hunt, dig, shop and scrape meant from bones.
Who are homo neanderthalensis an what tools did they use?
Lived beween 300,000 and 25,000 years ago
They made complex tools. There is evidence that they used flint tools, with sharp, pointed edges and wooden spears.
Who are Homo sapiens and what tools did they use?
Modern humans
The first h.sapien appears about 200,000 years ago,
By this point the flint tools were widely used. More complex pointed tools, including fish hooks, needles and arrowheads appeared around 50,000 years ago
How are tools dated?
- Looking at the structural features of the tool or fossil
- Using stratigraphy - the study of rock layers
- Carbon dating
Whaat is the pentadactyl limb?
A limb with 5 digits
How does the pentadactyl limb provide evidence for evolution?
The similarity in bone structure
If they’d all evolved from different ancestors, it’d be highly unlikely that they’d share bone structure.
What are the five kingdoms oof the “Five Kingdom Classification”?
- Animals
- Plants
- Fungi
- Prokaryotes
- Protists
What order are organisms classfied?
Kingdom Phylum Class Order Family Genus Species
What is selective breeding? (AKA artificial selection)
When humans pick particular plants or animals with (or without) specific traits so that those characteristics stay in (or out) of the population
Examples for uses of selective breeding
Animals that produce more milk or meat
Crops with disease resistance
Dogs that are gentle
Plans that produce bigger fruit
Process of selective breeding
- Select individuals (M&F) with desired trait
- Breed them with each other
- Select the best offspring and breed those together
- Continue two breed and select for desirable trait
Disadvantages of selective breeding
Reducing the gene pool which could result in poor health or disease susceptibility
What is tissue culture?
When cells are cultured outside of their natural place.
What is genetic engineering?
To transfer a gene from one organisms genome into another
What is GMO?
Genetically modified organism
An organism which has had a gene genetically engineered inside.
Examples of genetic engineering…
Bacteria can be engineered tooo produce insulin that can be used to treat diabetes
Crops for improving size or durability to drout
Cows oor sheep to produce useful human proteins in their milk which can be used to treat arthritis, multiple sclerosis etc.
How does genetic engineering work?
- DNA is cut with a restriction enzyme. Each RE recognizes a specific palindromic DNA sequence and can cut the DNA only at these spots. The cutting leaves a “sticky end”.
- Vector is cut open using the same restriction enzyme
- The vector and insert with the matching “sticky ends” are incubated with ligases and join up to produce recombinant DNA
- The recombinant DNA can be put into new cells and the cells can express the protein which the plasmid codes for.
Benefits for genetic engineering
Herbicide resistant crops
Insulin in bacteria for treatment of diabetes
Can increase a crop yield
- Resistant to pests
- Survive in drought
To produce certain nutrients which could help combat deficiencies in developing countries
- E.g. Vitamin A - golden rice
Disadvantages for genetic engineering
Ethical concerns- embryos don’t always survive
Horizontal transfer of resistant genes in plants - i.e. weeds could become herbicide resistant
GM crops may adversely effect e food chain or human health
Why use GM crops?
For “food security”
Disadvantages for GM crops as a response to food security
People argue that others go hungry because they can’t afford food, not because there isn’t any so poverty is the main issue, not food scarcity
Fear that countries may become dependent on companies selling GM seeds
Sometimes the problem is poor soil which can’t be fixed with current GM
Concern for long term effects on human health of exposure to GM crops.
What is a Bt crop?
Bacillus thuringiensis
A type oof bacterium that produces a toxin which is harmful to the larvae of insects that kill crops.
The gene for Bt can be inserted to the crop and expressed in their leaves and stem to protect from insect invasion.
Bt toxin is harmless to humans, animals and other insects.
Benefits of Bt crop
Increase crop yield
Reduce the needs for chemical pesticides which are harmful to the environment
Disadvantages of Bt crop
The insects are frequently exposed to the toxin so there is a chance they will become resistant to it.
- Farmers try to overcome this by using other insecticides too.
Other GM methods for increasing food production - Fertilizer - what is it?
Advantages and disadvantages
Helps to alleviate issues with bad soil. It contains minerals essential for plant growth, e.g. nitrates and phosphates
However, excess fertilizer can cause eutrophication in the surrounding water sources
What is eutrophication?
An excess of nutrients in the water which leads to algal blooms and the death of aquatic organisms
Other GM methods for increasing food production - Biological control - what is it?
e.g.s in agriculture around the qworld
Advantages and disadvantages
Use of other predator or parasite organisms to eliminate pests
e.g. Cane toad (native to South and Central America, and Southern USA) were introduced into Australia trot eat beetles that were damaging sugarcane crops
This can have longer lasting effects than chemical pesticides and be less harmful to wildlife in the Shortt-term. However, introducing new wildlife to a region can cause problems. e.g. Can toads are now pests themselves in Australia because they poison the native predator species that eat them.
What is a disease?
A condition where part of an organism doesn’t function properly.
WHO definition for health:
Health is a state of complete physical, mental and social well-being, and more merely the absence of disease or infirmity.
Two types of diseases:
Communicable and non-communicable
What is a communicable disease?
Those that can spread between individuals
Caused by things like bacteria, viruses, parasites and fungi. They’re sometimes described as contagious or infectious diseases.
