Biology Higher 3 GCSE Flashcards
What are the 2 main types of cells
Eukaryotic- Have a nucleus and are relatively large, between 10µm and 100µm
Prokaryotic cells- Don’t contain a nucleus. Usually bacterial cells. Their genetic material floats around in the cytoplasm. Usually between 1µm to 10µm.
µm to mm
divide by 1000
Examples of prokaryotic cells
E.coli- causes an upset stomach
Streptococcus- causes a cough
What happens in the nucleus
Controls the activities of the cell and holds the genetic material. Also contains the instructions needed to make new cells or organisms
What happens in the mitochondria
Where respiration happens. Glucose and oxygen react to make energy
What happens in the cell membrane
A selective barrier that controls what enters and leaves the cell. Also contains receptor molecules
What happens in the Cytoplasm
A ‘jelly-like’ substance where the chemical reactions to keep the cell alive happen.
What are extra subcellular structures the plants need
Vacuole- cell sap, that helps to keep the cell rigid and firm
Cell wall- Surrounds the cell and is made of cellulose fibre, keeping it rigid.
Chloroplast- Contains Chlorophyll, which transfers energy from the Sun to the plant, used in photosynthesis.
Subcellular structures that prokaryotic may have
Flagella: allows the cell to swim through liquids
Pili: hair-like structures that allows the cell to attach to structures like your digestive track.
Slime capsule: Outside the cell wall and protects the cell from drying out, and stick to smooth surfaces.
Plasmid: Used to store extra genes May be used in times of stress.
Why do we have to stain cells
Most cells are actually colourless so stains are used to make them easier to observe and to see.
How can you use a stain
Put the cell on a glass slide
Add 1 drop of stain
Put a plastic coverslip on top
Tap the coverslip gently to get rid of any air bubbles
Stains
Methylene blue - nucleus of animal cells
Iodine - nucleus of plant cells
Crystal violet- bacterial cell walls
what is an electron microscope
they use electrons instead of light to produce an image
2 types of electron microscopes
Transmission Electron Microscope- a beam of electrons passes through a very thin slice of the sample
Scanning Electron Microscope- Produces a 3D image by sending a beam of electrons across the surface of the specimen, so the reflected electrons can be used to produce an image
Pros and cons of an electron microscope
Expensive Difficult to move Sample preparation is complex Specimens must be dead Black and white images are produced, but false colour can be added High resolution
Pros and cons of a light microscope
Cheap Small and portable Simple to prepare a sample Natural colour of stain is seen Specimen can be living or dead.
What is in a DNA nucleotide
Phosphate
Deoxyribose
Base
How many chromosomes do you have
46
What is a gene
A shorter section of a DNA
Transcription
- DNA unzips
- mRNA comes in
- One of the strands acts as a template as the complementary bases are attached
(U instead of T) - mRNA comes off
- DNA zips
mRNA moves to the ribosomes in the cytoplasm
Translation
3 Bases join together to make an amino acid. These join together to make long chain, a protein. The ribosomes read the mRNA in groups of three, called codons.
What is the active site
On the enzyme, the space where the substrate fits
what factors affect enzyme controlled reactions
temperature
(denatured)
pH
Substrate concentration
What is a metabollic rate
The speed at which your cells can transfer energy from its food to chemical stores.
What does lipase break down
Lipids- 3 fatty acids and 1 glycerol molecule
Where is there a lot of mitochondria
muscle cells
because they are contracting and need energy
Anaerobic respiration in humans
When there is a lack of oxygen and the glucose isn’t broken down properly
It produces lactic acid instead
Anaerobic respiration in plants
fermentation
C6H12O6 -> 2C2H5OH + 2C02
Stages in photosynthesis
Stage 1: Light dependant- light is used to split water into hydrogen and oxygen.
Stage 2: Light independent- carbon dioxide combines with hydrogen to make glucose
what happens to the glucose produced
cellulose- cell walls proteins- growth and repair fats and oils- food store and growth sucrose- stored in fruit starch- food store
factors affecting photosynthesis
light intensity
carbon dioxide
temperature
rate of photosynthesis
rate = 1/ timw
relative light intensity
rli= 1/ distance from light source2 (squared)
how can you change the co2 concentration
add different masses of potassium hydrogen carbonate powder to the water
how can you change temperature
water bath
diffusion
movement of particles from an area of HIGH CONCENTRATION to an area of LOW CONCENTRATION
Factors affecting diffusion
decrease the distance
increase surface area
increase concentration gradient
Osmosis
diffusion of water across a selectively permeable membrane from an area of HIGH WATER POTENTIAL to an area of LOW WATER POTENTIAL
Active transport
Uses energy and carrier proteins to transport molecules from an area of low concentration to an area of higher concentration
Examples of active transport
Glucose transported into the bloodstream
In nerve cells- pumps out sodium and potassium back in
Mitosis
IPMATC
Why do we need mitosis
It helps to repair damaged tissues, and replace worn out cells.
2 identical daughter cells are made
How is a sperm cell specialised
It has a
flagella
lots of mitochondria
acrosome
where are stem cells found in plants?
a plant doesn’t stop growing, but only the meristems grow, because they can differentiate
they have very thing walls, small vacuoles and no chloroplasts compared to other plant cells
when do the guard cells open?
when there is enough light and water. They swell up and become turgid
Why do plants wilt
If a plant loses more water than it can take in.
what causes short-sightedness
eyeball is too long or the lens is too strong
needs a concave lens to be fixed
what causes long-sightedness
eyeball is too short or the lens is too weak
needs a convex lens to fix it
What does the suspensory ligament do
It connects the ciliary muscle to the lens
when does the lens become convex
ciliary muscle contracts and the lens becomes fatter
when does the lens become concave
ciliary muscle relaxes and the lens becomes thinner
what do rods and cones do
rods- respond to light in dark
cones- respond to different colours
what does the cerebrum do
learning, memory and personality
what does the hypothalamus do
water balance and temperature
what does the pituitary gland do
releases hormones
what do the cerebellum do
posture and balance
what does the medulla do
involuntary actions such as breathing rate and heart rate
how can you investigate brain function
Computer Tomography-
Use X-Rays to create 3D images of anywhere in the body, and the position of any abnormalities
MRI- Magnetic Resonance Imaging
Powerful magnets to identify brain abnormalities. (fMRI does the same in real time) They show areas of the brain with increased blood flow.
Ethical problems with investigating brain function
patients must give consent for their information to be given
Many case studies need to be analysed to draw a conclusion
Several areas of the brain may be used at one point
Animal testing is bad
FSH
Follicle Stimulating Hormone
Secreted by the pituitary glands
travels to the ovaries where is causes the egg to mature
Also stimulates the ovaries to produce oestrogen
LH
Luteinising Hormone
When levels of this reach a peak, ovulation is triggered
Oestrogen
Causes the lining to be built up
Made by the ovaries
As this rises, it inhibits the production of FSH, preventing more than 1 egg maturing
Progesterone
Maintains the uterus lining
Inhibits LH
Types of contraception
Non-hormonal: Barrier methods that prevents physical contact
Hormonal: It uses hormones to disrupt the female reproductive system
Non-hormonal contraception:
Condom
Intrauterine device
Cervical cap
Condom
Placed over the penis to prevent the sperm entering the vagina
Prevents STDs
Cervical cap
Inserted into the vagina to cover the cervix. Removed 6 or more hours after the sexual intercourse
Must be used with spermicide
Intrauterine Device
Inserted into the uterus and releases copper to kill the sperm. Remains effective for 5 to 10 years
Hormonal Contraception
Combined pill
Progesterone pill
Intrauterine System
Combined pill
Prevents ovulation by thickening the mucus, stopping the implantation into the uterus lining
Must be used 21 days of the menstrual cycle
Progesterone pill
Thickens mucus and thins the lining of the uterus so there physically can’t be a implantation.
Must be taken at around the same time daily
Intrauterine System
Thickens mucus and thins the lining of the uterus so there physically can’t be a implantation.
Effective for 3-5 years
Causes of infertility
blocked sperm ducts
not enough sperm
lack of mature eggs
failure to release an egg
Fertility treatment- using hormones
FSH- can be given to stimulate her eggs to mature.(triggering oestrogen production)
IVF
Collecting eggs and sperm, then mixing them outside of the body. then implanting it back into the mother
Considerations with ivf
Multiple pregnancies failure Not natural Allows people to have children Expensive Allows women to focus on their careers and have children later
Phototropism
Gravitopism
Growing towards the light
Growing in the same direction as gravity
Uses of ethene
Ripening fruit by stimulating the conversion of starch into sugars.
Uses of gibberellins
Promotes growth. Uses to control dormancy
Uses of auxins
Killing weeds (uncontrolled growth)
Promoting root growth (used for cloning and they will dip the stem into it)
Delaying ripening
Produce seedless fruits (Apply auxins to unpollinated flowers)
Type 1 Diabetes
Cannot produce insulin
Immune system kills cells
Begins at childhood
Type 2 Diabetes
Cannot use the insulin
Linked to obesity
Where does ultra-filtration happen
Bowman’s capsule
Where does selective reabsorption happen
in the area after the bowman’s capsule
where does salt and water regulation happen
loop of henle and the collecting duct
Where does protein go
It’s too large to fit in the capsule so it stays in the bloodstream
What happens in the selective reabsorption
glucose is all reabsorbed
sometimes some salt and water is reabsorbed too
what happens in the salt and water regulation part
according to the amount of ADH etc, salt and water may be taken away
isotonic
contains the same amount of ion concentrations as the blood
hypertonic
more glucose and salts
hypotonic
less glucose and salts
CNS
Consists of the brain and the spinal cord
PNS
Consists of all the neurones that connect the CNS to the rest of the body.
Damage to your CNS or PNS could occur from
Injury
Disease
Genetic condition (Huntington’s disease)
Ingesting a toxic substance such as lead
Damage to PNS can cause:
Inability to detect pain
Numbness
Loss of coordination
Damage to the CNS can cause:
Loss of control of body systems
Paralysis
Memory loss or processing difficulties
Can the CNS or PNS regenerate?
The PNS can regenerate and minor nerve damage often self heals.
However, CNS can’t regenerate.
Treatments for the brain
Radiotherapy (brain tumours)
Chemotherapy (brain tumours)
Surgery to remove damaged brain tissue
Deep brain stimulation- inserting an electrode to stimulate brain function
Why is the CNS so hard to repair?
The spinal cord consists of 31 pairs of nerves and each has many nerve fibres. Each spinal cord is about 1.5 cm in diameter so it is quite hard to identify and repair something without damaging something else.
higher temperatures in enzymes means what
they can reproduce faster
they are closer to their optimum temperature
they can respire faster
there are more successful collisions because there is more energy for the particles to move faster into each other, meaning the rate of the reaction increases
HOWEVER
Enzymes may unravel and denature
This is when the active site changes shape and the enzyme is no longer specific, so it means that the substrate can’t fit in the active site anymore, so the rate will decrease.
What are embryonic cells used for
Development and growth
What are adult stem cells used for
Repair and replacement
What is differentiation
When cells become specialised at one job.
How can shoot tips of a plant regenerate into a whole plant
The shoot tips of a plant are made up of meristem tissues. They produce unspecialised cells that can be divide and form any type of cell, being able to regenerate an entire plant.
Outline how multicellular organisms and single called organisms exchange substance and explain why they exchange substances differently
Single called organisms can rely on diffusion alone to exchange substances because they are so small.
It is fairly quick because the distance to travel is quite small, and they have a larger surface area to volume ratio.
In multicellular organisms, diffusion would take too much time due to the low SA:V ratio. Therefore, they use their own specialised exchange organs to exchange substances, they have their own transport systems.
Functions of air spaces in leaves
Gases can move easier between the cells and they increase surface area to volume ratio for gas exchange.
How is water taken up by root hair cells
The water travels up by osmosis. There is a high concentration of water in the soil compared to the roots. The water travels cell by cell until it reaches the xylem.
How is the small intestine changed to carry out it’s function
It has vili, which increases it sa:v ratio for absorption, allowing it to happen quickly. The small intestine has a good blood supply. The vili have 1 single layer for surface cells, meaning the gases don’t need to travel a large distance to be absorbed.
Why is the human circulatory system described as a double circulatory system
It consists of 2 circuits joined together, the first circuit pumps deoxygenated blood to the lungs and returns with oxygenated blood. The second pumps oxygenated blood to the body and return with deoxygenated blood.
It goes around twice in the heart in one cycle.
Why is a double circulatory system good
It can be pumped out of the heart at higher pressures, increasing blood flow to the tissues, meaning more oxygen can be transported.
What is in blood
Plasma (water, hormones and antibodies, amino acids, glucose etc. )
Red blood cells - carry oxygen
White blood cells- have antibodies
Platelets- allows the blood to clot.
Xylem walls
They are thick, made form lignin and they give the plant support.
