B1 Flashcards
Eukaryotic cells
Contain nucleus
Prokaryotic cells
No nucleus, genetic material floats in cytoplasm
Sperm cell
-flagellum
- mitochondria
- streamlined
-digestive enzymes
Three Stem cells and where they are found?
- adult stem cell- bone marrow
-embryonic stem cells- embryo - plant meristems- roots&shoots of plant
What are plant meristems used for
- cloning rare plants
-protecting rare species
-food security
Why are embryonic stem cells better than adult stem cells?
Embryonic stem cells can differentiate into any cells where’s adult stem cells can only turn into specific types of cells.
Cell cycle & describe mitosis
DNA replication
Mitosis
Cytokinesis
Growth
3 things that happen during respiration when exercising
- blood vessels dialate
- increased breathing
- increased heart rate
Oxygen debt is…
Extra oxygen required after exercise to oxidise lactic acid and remove it from cells
Why is aerobic respiration more efficient than anaerobic respiration?
Anaerobic respiration doesn’t break down glucose completely whereas aerobic respiration does so aerobic respiration produces more energy
What is a gene?
Short section of DNA which codes for specific protein
Chromosome?
Long strand of DNA
Nucleotide is…
Units that make up DNA bases
Lipasew
- turns lipid to fatty acids & glycerol
- small intestine
Protease
- turns protein to amino acids
- small intestine & stomach
Amylase
-turns starch to maltose
- in mouth and small intestine
which of carbohydrates, protein and lipids are polymers?
Carbohydrates and protein
Test for protein
-Biuret solution purple if present
Starch test
-iodine , blue if present
Sugar test
Benedict - yellow,red,green if present
Lipid test
Emulsion test - milky if present
Light intensity
1/distance squared
Increases rate of transpiration?
Light intensity
Increase in temp
Increase in air flow
Decreases rate of transpiration
Air humidity , lowers conc gradient
Guard cells open when…
Turgid
Guard cells close when….
Flaccid
order of tissues in plant
Epidermal tissue
Palisade mesophyll
Spongy mesophyll
Stomata
Purpose of stomata
Little gaps to allow carbon dioxide to diffuse in and oxygen + water diffuse out
Purpose of waxy cuticle
Makes plant waterproof
Purpose of epidermal tissue
Transparent to allow light to pass through
Purpose of palisade mesophyll
- has lots of chloroplast to absorb light for photosynthesis
Purpose of spongy mesophyll
- gaps between cell to allow carbon dioxide and oxygen to pass through easily
What is transpiration?
When the plant opens its stomata to let in carbon dioxide, water on the surface of the cells of the spongy mesophyll and palisade mesophyll evaporates and diffuses out of the leaf.
Water is drawn from the cells in the xylem to replace that which has been lost from the leaves.
Water is moved from roots to leaves
What is translocation?
The movement of nutrients and food around a plant using the phloem around the plant like the roots.
What is a potometer?
It is used to estimate transpiration rate
Transpiration rate
Distance moved / time taken
Why do you cut the shoot underwater?
To prevent air entering the xylem
Why do you cut the plant at a slant?
To increase the surface area available for water uptake
What independent variables can be changed to see how environmental conditions affect rate of transpiration?
- use a lamp to increase intensity
- use a fan to increase air movement
- increase temperature in the room
If the cell is small what would happen to the surface area: to volume ratio?
It would be big
Why do single celled organisms not require exchange surfaces?
They can diffuse straight into and out of single felled organisms across the cell membrane since there is a short distance and high surface area:volume ratio
2 main parts of CNS
spinal cord and brain
Sclera
White of the eye
Purpose of cornea
Transparent layer, Refracts the light rays which enter the eye and help focus them on the retina
How does the eye focus on close objects ?
The ciliary muscles contract, The suspensory ligaments slacken , so the lens thickens. This means the light is refracted more, so the light can focus in the retina.
What happens to the pupil in low light conditions?
The pupil gets larger , the circular muscles relax
What happens in bright light situations?
The pupil gets smaller, circular muscle contract
What happens to the muscles when the pupil constricts
Circular muscles contract , radial muscles relax
What happens to the muscles when the pupil dilates?
The circular muscles relax, the radial muscles contract.
Which two muscles control the shape of the lens?
Ciliary muscles and suspensory ligaments
What does the lens need to look like when focussing on a close object?
Short and fat, more curved
How does the eye focus on distant objects?
The ciliary muscles relaxes and The suspensory ligaments pull taut, which stretches the lens. This means the light is refracted less, so the light can focus on the retina.
Long sighteness
Hyperopia
Short sightedness
Myopia
Why does a long sighted person struggle to see near objects?
Eyeball too short , so light focuses behind retina
Why does a short sighted person struggle to see far things?
Eyeball is elongated so light focuses infront of the retina
How to fix myopia?
Concave lens
How to fix hyperopia ?
Convex lens
What hormones prevent pregnancy
Oestrogen- inhibits FSH so no mature egg is released
Progesterone- stimulates thick mucus so sperm can’t reach egg
What hormones help stimulate pregnancy?
FSH- helps egg mature
LH- helps stimulate release of mature egg
In shoots, auxin….
Promotes growth and elongation
In roots auxin…
Inhibits growth and elongation
What would happen to a positively phototropic plant?
Grows towards light
What happen to the side of the plant facing the sun?
Auxin breaks down
What happens to the shaded side (away from the sun)?
Auxin collects on the shaded side, leading to uneven distribution of auxin in shoots.
This leads to growth and elongation in the shaded side but not the sunny side so the plant grows towards the sun, showing positive phototropism.
What phototropism and gravitropism look like in the shoots?
Positive phototropism and negative gravitropism
Negatively phototropic
Away from light
Positively gravitropic
Towards the ground
Negatively gravitropic
Away from ground
In the roots the upper side will….
Grow faster, since the lower side inhibits growth
What happens to a gravitropic plant?
Grows downwards towards gravity
Where do auxins collect on a gravitropic plant?
It collects on the underside of the plant due to the pull of gravity.
Use of auxin?
Stimulate plants to grow
Weed killer
Gibberellin use?
Controlling dormancy
Inducing flowering
Growing larger fruit
Ethene use?
Stimulate ripening of fruit
Homeostasis
Stable internal environment
What are Receptors?
They detect changes in our body temperature
When your in a very cold place your body warms up by….
- vasoconstriction, constrict blood vessels, lesss heat energy lost
- shivering
- hair stand up
When your very hot and try to cool down your body…
- vasodilation- blood vessels dilate so more heat energy lost to surroundings
- sweat
What happens when glucose levels are too high?
Pancreas releases insulin into bloodstream.
Insulin binds to receptors on certain cells like liver/muscle, tells them to take in extra glucose.
Turns extra glucose into glycogen, storage of glucose
What is glycogen?
A storage form of glucose
What happens if glucose levels are too low?
Pancreas secretes glucagon into bloodstream.
Binds to cells mainly liver cell, breaks down glycogen to glucose
What is type 1 diabetes?
When your body doesn’t produce insulin
What is type 2 diabetes?
When your body doesn’t respond to insulin
Treatment for type 1?
Insulin injections
Manage diet
Exercise
Who usually gets type 1 and is it lifelong?
People of young age during childhood
It is lifelong
Who usually gets type 2 and why
Older people, overweight people
Treatment for type 2?
Exercising
Managing diet
What does too much glucose to do the body?
Affects osmosis
What does too little glucose do to the body?
No energy is produced since glucose is requ
What is deamination ?
Excess amino acids converted into lipids and carbohydrates
What does ADH do to water conc levels?
Increase water concentration
Too little water in the body?
Too much water in body?
Which gland releases thyroxine?
Thyroid
Which gland releases adrenaline?
Adrenal gland
What is thyroxine used for?
To regulate rate of metabolism
What does the pituitary gland do?
Tells other glands to release their hormones
What do the pituitary glands do if there are low thyroxine levels?
Pituitary glands stimulate TSH which brings thyroxine levels back up
What hormone does Pancreas secrete?
Secrets insulin
What does adrenaline do?
Increase heart rate
Increase blood pressure
Increase blood flow to muscles
Increase glucose levels
Thyroxine levels too high?
Thyroxine inhibits pituitary gland from releasing TSH. Less TSH= less thyroxine
Homeostasis?
Maintains a stable internal environment
Receptors > co ordination centre> effector
Receptor
Detects change
Effectors?
Muscles contract
Glands release hormones
Central Nervous system
Stimulus> receptor> sensory neurone> CNS> motor neurone >effector > response
Reflex arc?
Stimulus
Sensory neurone
impulse CNS
relay neurone
Motor neurone
Effector
Response
