Mock exam Flashcards
Electron microscope
Microscope that uses a beam of electrons to create an image of the specimen. Has higher magnification and a greater resolution than a light microscope.
It can allow us of see much small objects in finer detail
Formula triangle for magnification
I
A M
Definition of resolution
The ability to distinguish two objects from eachother
Why can some cell structure be seen with a electron microscope that not with a light microscope
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Effect of temperature on enzyme activity
As temperatures increase so does enzyme activity
37* is the optimum temperature (body temp)
To low or to high will denature enzyme
Effect odf
Alter enzymes shape
Different enzymes work best in different ph values.
E.g.- stomach enzymes -ph 2
Intestinal enzymes- ph 7.5
Effects of substrate concentration on enzyme activity
Increasing substrate concentration increases the rate of reaction. This is because more substrate molecules will be colliding with the enzymes therefore more product will be formed.
What is growth In animals also known as
Increase in cell number and size
Examples of specialised animal cells
Neuron cell
Red blood cell
Sperm cell
Adaptions of the
Neuron cell
Red blood cell
Neuron cells are really long so they can communicate over long distances and have ends called dendrites which connect with other neurons
Red blood cells have no nucleus so they have more room to store haemoglobin, bioconcave shape to maximise oxygen absorption and they are flexible
What is a growth in an animal also known as
Increase in cell number and size
Specialised plant cells
Xylem cell
Root hair cells
Adaptions of the specialised plant cells
Xylem cells are hollow so they can carry water and minerals to trunk from the Roots and altered cell walls so they can allow passage of one vessel to another
Root hair cells have a large surface area to speed up and maximise osmosis
How are ciliated epithelial cells adapted to their function
The cilia are tiny hair like structures on the surface of the cell, the hairs sweep mucas and dust and bacteria up to the back of the throat where it can be swallowed
What are specialised cells
A cell that has been created and adapted for a specific function, their structure will allow them to carry the function out.
Eukaryotic cell
Has a nucleus Linear DNA Don't always have a cell wall Found in all Kingdoms E.g.- plant Animals Fungi Ribosomes
Prokaryotic cell
No nucleus Found in kingdom monera Single circular DNA Haploid Single celled organisms E.g. Algae, bacteria
Why is bacteria prokaryotic?
It doesn’t have a membrane bound nucleus
Common parts of bacteria
Cell wall- often the target for antibiotic treatment
Don’t have nucleus
Some have flagellum to move around
Two types of DNA- plasmid (small loop that carries extra information) and chromosomal (carries genetic information)
Calculation to find out the rate of enzyme activity
Rate of higher temp \ rate of lower temp
Why are enzymes important for life processes
Allow reactions to happen a lot faster, without them reactions would occur to slowly to keep you alive
What are enzymes
PROTEINS
Biological catalysts
Subunits from which carbohydrates, protein and lipids are formed
Sugars
Amino acids
Fatty acids
Glycerol
What do enzymes do
Speed up the rate of chemical reactions within cells
Calculation in percentage gain or loss of mass in osmosis
(End mass - start mass) / start mass *100
How are substances transported by osmosis
Movement of water from a less concentrated solution to a more concentrated solution through a semi permeable membrane
E.g.-plants roots absorbing water
How are substances transported by diffusion
Diffusion is the process in which particles spread out and then move from a region of high concentration to a region of low concentration. Particles of a substance will move down a concentration gradient until they are evenly spread e.g. Gas exchange in the lungs
How are substances transported by active transport
Active transport is the process by which dissolved molecules move across a cell wall membrane from a lower to a higher concentration. In active transport, particles move against the concentration gradient therefore requires an input of energy from a cell.
E.g. Minerals through root hair cells in plants
What’s an active site
An enzymes action and a region \ part of enzyme that bands to a protein or other substance during reaction.
How to test foods for starch
A drop of Iodine into the substance and if turns a dark purple starch is present
How to test foods for protein
Add drops of biurets solution and if it turns a purple then it has protein
How to test food for simple sugars
Add Benedicts solution to tubes of food and place test tubes in a beaker of boiling water.
If food in test tube produces an orange precipitate (solid mixed through liquid) it shows it could contains lots of sugars.
If a green precipitate is formed then it shows that only a small amount of sugar is present.
Parts of a plant cell
Nucleus Cytoplasm Cell membrane Chloroplasts Vacuole Cell wall Mitochondria
Parts of animal cell
Nucleus
Cytoplasm
Cell membrane
Mitocondria
Names and order of stages in mitosis
Prophase
Metaphase
Anaphase
Telophase
Describe what happens in each stage of mitosis
P- chromosomes in nucleus are copied
M-chromatids pulled apart and moved towards poles
A- chromosomes separate
T- cell divides
Why do some organisms rely on asexual reproduction
It’s quicker and less energy
How does mitosis produces genetically identical diploid cells
Cell copies its chromosomes then splits the copied chromosomes equally to make sure that each daughter cell has a full set
How do cancers grow?
Sometimes cells in part of a multicellular organisms divide uncontrollably causing a lump ;The result is a large mass of cells called a tumour. If tumour cells successfully invade other tissues in the body the result is cancer.
Function of stem cells in plants and animals
Treat diseases
Replace cells
Grow limbs
Testing new drugs
Differences between embryonic and adult stem cells
Embryonic stem cells come from an undeveloped embryo and can develop into any type of cell, whereas adult stem cells are unspecialised cells that can develop into many (not all) types of cell.
Examples of when stem cells have been used in medicine
Making new Brian cells to treat people with Parkinson’s disease
Rebuilding bones and cartilage
Repairing damaged Immune systems
Making replacement heart valves
Benefits and risks of using stem cells in medicine
Can help to cure and grow new cells
Cure diseases
Expensive
BUT there is a Risk of uncontrollable growth causing cancer
Still new and hasn’t been fully explored
Ethical reasons
Name the 3 main parts of the brain
Cerebellum
Cerebral hemisphere
Medulla oblongata
What does the cerebellum do
Receives information from the sensory systems. It coordinates voluntary movements such as posture, balance, speech etc
What do both the cerebral hemisphere do
Right coordinates left and left coordinates the right.
Function of the medulla oblongata
Helps regulate breathing, heart and blood vessel function, digestion, sneezing and swallowing. This part of the brain is a centre for respiration and circulation.
Sensory and motor neurons travel through the medulla.
What is CT and PET scanning
PET uses small amounts of radio active materials called radiotracers, a special camera and computer that can help evaluate your organ and tissue functions, it can help detect disease early on.
CT scan uses X-rays to make detailed pictures of the inside of your body, used to asses head injuries and causes of stroke
Effects of spinal cord damage
Back pain
Pressure in neck or head or back
Weakness
Incoordination or paralysis in any part of body
Numbness
Tingling
Loss of sensation in hands fingers feet or toes
Effects of damage to different parts of the brain
Cerebellum- loss of ability to walk, coordinate fine movements, slurred speech and dizziness.
Cerebral hemispheres- if injury was sustained to the left side of the Brain the right side would be effected eg- paralysis of limbs
Medulla oblongata- stop swallowing, drooling and
Paralysis
Why can’t some types of spinal cord damage not be repaired fully
Some cells of the central nervous system are so specialised that they cannot divide and create new cells
Parts of the nervous system
Brain and spinal cords, and nerves (neurons)
How does the nervous system detect stimuli
Receptors are located in the sense organs e.g. Ear eye and skin. Each organ has receptors sensitive to particular kinds of stimuli
List the main parts of the eye
Cornea
Lens
Iris
Retina
Explain how the cornea, lens, iris and retina are adapted to their functions
Cornea- convex and transparent. It refreacts light as if enters the eye
Lens- transparent, bi convex. It focuses light onto the retina
Iris- pigmented, eye colour is decided by iris. , Responsible for controlling the diameter and size of the pupil (by muscle contraction) and thus the amount of light reaching the retina.
Retina- back of the eye containing 2 cells, a rod that’s sensitive to dim light and bw and cones that are sensitive to colour. CONTAINS LIGHT RECEPTORS
Common eye defects
Cataracts
Long/short sightedness
Colour blindness
How are cataracts treated
Improved with sunglasses or , magnifying
Lenses. OR surgery can. Remove cloudy lens and replace it with an artificial lens
Describe features or asexual reproduction
Quick
No need for a mate
No variation of offspring
Describe features of sexual reproduction
Slower
Requires a mate
Variation in offspring
Advantages and disadvantages of asexual reproduction
Advantages- rapid populating& can exploit a suitable habitat quickly
Disadvantages- no variation within population, disease may effect all the individuals in a population, species may only be suited to one habitat
Advantages and disadvantages of sexual reproduction
Advantages- introduced variation, species can adapt to new environments and diseases is less likely to affect all In a population.
Disadvantages- time and energy needed to find a mate, not possible for an isolated individual
What are produced in meiosis
Gametes
What happens in meiosis
Same as mitosis but x2
Homologous chromosomes separate to create 2 daughter nuclei
The 2 daughter nuclei divide, chromosomes themselves are separated. Creates 4 gametes
Genome
An organisms complete set of DNA
Where are genes found
In DNA
What do genes do
Code for specific characteristics of phenotypic traits
Where is DNA found in a eukaryotic cell
Nucleus
Name the 4 bases of DNA
Adenine
Cytosine
Thymine
Guanine
What are the paring of bases of DNA
A and T
C and G
How are strands of DNA held together
By hydrogen bonds between pairs of bases
Where are proteins made
Ribosomes - they strung together long chains of amino acids
How is the order of amino acids in protein determined
Each triplet of bases code for one particular amino acids, they are dictated by the number and order of base triplets
Transcription
1-In the nucleus DNA is split in half by helicase
2-Strands created are the non coding and coding strand
3-RNA polymerase joins to the non coding strand of DNA at the beginning of the gene
4-Complementary bases attach to the strand being copied- C-G and U-A (uracil replaces Thymine)
5-RNA then copies DNA into an exact copy of RNA called mRNA
Translation
1-The mRNA leaves through the nucleus pores and u to the cytoplasm where it joins to ribosomes
2- tRNA molecules transport specific amino acids to the ribosome
3-each mRNA codon codes for a specific amino acid
4-anti codons and codons match up and form complimentary base pairs
5-a polypeptide chain is formed - PROTEIN
What’s a mutation
A change in the DNA
How Can mutations occur?
Caused by environmental factors such as ultraviolet radiation
Hereditary mutations
DNA fails to copy accurately
Who discovered the basis of genetics
Gregor Mendel
How was breeding pea plants used to work out the basis of genetics
He cross bred distinctively different plants and discovered that there are dominant and recessive traits passed on. He also discovered that traits from the parents were given to offspring
What’s the difference between a gene and an allele
Genes are a short section of DNA and an alleles are different forms of a gene, they can be dominant or recessive.
Relationship between the phenotype and genotype
The genotype of an organism is defined as the total sum of all the genes. The phenotype of a organism is the observable physical characteristics of an organism.
Homozygous and heterozygous
Homo- a certain gene carrying two copies of the same allele
Hetro- a certain gene carrying two different alleles
How is sex determined in humans
A chromosome from a sperm cell, either X or Y,fuses with the X chromosome in the egg cell.
If the X fuses it’s a girl (XX)
If the Y fuses it’s a boy (XY)
Examples of sex linked genetic disorders
Haemophilia
Colour blindness
Characteristics controlled by multiple genes
ABO blood groups
Hair colour
Hair texture
Eye colour
How can mutations cause variations.
Mutations produce random changes in an organisms genetic code, this causes a different protein to be produced or none.
Why do many mutations have no effect on the phenotype
A mutation could occur in a stretch of DNA with no function or not affecting amino acid sequence of protein
Continuous and discontinuous variation
Continuous is when there is no limit on the value that can occur in the population e.g.- height, weight and finger length
Discontinuous is when there are distinct groups and it is limited e.g. Blood group, tongue rolling and finger prints
Causes of genetic variation
Mutations
Sexual reproduction
Causes of environmental variation
Differences in the environment
Acquired / adapted characteristics
How is a sperm cell adapted to its function
Acrosomes- enzymes which break the cell membrane of the egg cell to fertilise it
Haploid nucleus- half genetic info
Tail- swim
Mitochondria- energy and respiration
How is an egg cell adapted to its function
Nutrients in cytoplasm
Haploid nucleus- half genetic info
Changes in cell membrane after fertilisation
Define the terms
Chromosome
Gene
Allele
Chromosome- Rod shaped bodies found in the nucleus of cells that contains genetic information
Gene- a section of DNA which controls part of a cells chemistry
Allele- different versions of the same gene
Define a gamete and a zygote
Gamete- Sex cells - sperm and egg
Zygote- the cell formed form fertilisation which will then go on to form a embryo
How to extract DNA from fruit
Salt water mixed with soap with the mashed up fruit. Leave mixture for 15 mins at 60*. Then filter the mixture and pour iced ethanol on to the filtrate. The DNA floats to the surface.
Recall the 5 steps of a human detecting a stimulus and how we react
Receptors detect stimulus
Sensory neuron Carries message from receptor to CNS
Central nervous system
Motor neuron carries message from CNS to effector
Effector (muscles& glands )
reflex arc
Reflex arc is automatic and doesn’t require the brain therefore conserves energy and power e.g.- walking- reflex arc in foot
What’s the first thing to detect a change/stimulus
Receptors- found in our sense organs
What is the structure of a neuron like
Dendrites (branched endings) connected to dendron and an axon and to end - an axon terminal
What is the coating on dendrons and axons called and what does it do
It’s called a Myelin sheath and stops interference between neurons- insulator
What’s a synapse and how does it work
It’s the gap between neurons
It works as an impulse causes a release of a neurotransmitter chemical, this chemical diffuses across the synapse and the chemical binds to receptors on the next neuron
What is a meristem
The area in plants where cell division (mitosis) occurs.
What does the sensory neurone do
Carry signals from receptors (organ which recognises and responds to stimuli) to the spinal cord and brain.
What does the relay neurone do
Carry messages from one part of the CNS to another.
What does the motor neurone do
Carry signals from the CNS to effectors (muscle reaction/action)
Function of dendrites
Branch like structures at the start of the neurone that receive electrical messages
Function of dendron
Nerve fibres that transmit nerve impulses towards the cell body
Function of axon
Long projection of a nerve cell that conducts electrical impulses away from the neurons body and Transmits information to different neurons muscles and glands
Whats the monohybrid cross
Study of the inheritance of one characteristic
Axon terminal function
Releases the neurotransmitters over the synapse
Outcomes of human genome project
Mapping all of the genes of a human genome
- gives detailed information about chromosomes
- 3.2 billion bases molecules make up the DNA code
- further scientific knowledge and development
- help us learn more about genetic disorders
