B2 Flashcards
What are the similarities and differences of animal and plant cells?
Similarities:
Nucleus
Cytoplasm
Cell membrane
Differences: Only plant cells have: Cell wall Vacuole Chloroplasts
What are the different parts of an animal cell?
What are their functions?
Nucleus
Holds DNA for cell division and protein synthesis (mitosis)
Cytoplasm:
Where all the chemical reactions take place (e.g anaerobic respiration)
Mitochondria
(Within cytoplasm) Site of aerobic respiration
Cell membrane:
Controls what goes in and out of the cell
(Is selectively permeable- has gates that allow large molecules such as glucose to enter and leave but not smaller ones)
Ribosomes
Macromolecule structural clamping units that froms bonds between amino acids to create poly-peptide chains (proteins)
What are the different parts of a plant cell?
What are their functions?
Cell wall
Gives the cell a rigid shape and strengthens
(made of cellulose- complex sugar)
Vacuole
Keeps the pressure within the cell right
- Filled with cell sap
Chloroplasts
The site of photosynthesis (production of glucose)
Nucleus
Holds DNA for cell division and protein synthesis (mitosis)
Cytoplasm:
Where all the chemical reactions take place (e.g anaerobic respiration)
Mitochondria
(Within cytoplasm) Site of aerobic respiration
Cell membrane:
Controls what goes in and out of the cell
(Is selectively permeable- has gates that allow large molecules such as glucose to enter and leave but not smaller ones)
Ribosomes
Macromolecule structural clamping units that froms bonds between amino acids to create poly-peptide chains (proteins)
How do you calculate magnification?
Eye piece X Objective lens
OR
Size of image/ Actual size
What are the parts of a bacteria cell?
No defined nucleus
Cytoplasm
Cell membrane
Slime capsule
(keeps cell hydrated)
Cell wall
(made of murein not cellulose)
Loop of DNA
Ribosomes
Macromolecule structural clamping units that froms bonds between amino acids to create poly-peptide chains (proteins)
No mitochondria
Are bacteria unicellular or multicellular organisms?
Unicellular
Are fungi unicellular or multicellular organisms?
Unicellular
Are animals unicellular or multicellular organisms?
Multicellular
Are plants unicellular or multicellular organisms?
Multicellular
What are the parts of a fungus cell?
Cell wall
Cell membrane
Mitochondria
Nucleus
Vacuole
Cytoplasm
Name some differentiated cells
-How are they adapted for their use?
Guard cells (PLANT) -Change cells to open and close the stomata
Sperm cell
- Flagella for movement
- Haploid nucleus
- Acrosome at head to release enzymes to get through outer layer of egg (hydrolytic)
- Mitochondria- extra energy for movement
Red blood cell -bioconcaved disc -High SA -no nucleus = can fit optimum amounts of oxyhaemoglobin
Egg cell
- Haploid nucleus
- Large amount of cytoplasm- extra food stores
- Large amounts of mitochondria
Root hair cell
-High SA (due to hair-like appendages)
=can absorb optimum amounts of minerals/ions/nutrients
White blood cell- phagocyte
- Lobed nucleus
- -> can change shape to engulf pathogens
Neurone -Myelin sheath (insulates) -Dendrites (lots of connections possible)
Muscle cell
-Has striations that can contract and relax
What is the process of diffusion?
Particles using their kinetic energy to move down the concentration gradient until they eventually reach a dynamic equilibrium
What is the concentration gradient?
Movement from an area of high concentration to an area of low concentration
Why is diffusion important to organisms?
Because it allows the organism to access oxygen, glucose, water and carbon dioxide without using any energy
What happens when a cell needs to pump against the concentration gradient?
Active transport- The cell uses its membrane to push against using ATP
Why are cells small?
Its beneficial to them to have:
A large surface area to volume ratio
Short diffusion pathways to keep the cell alive
What is a tissue?
A group of specialised cells
What is an organ?
A group of tissues working with a common thing
Where does diffusion occur in the human body?
Digestion (w/ sugars)
Lungs (w/ gases)
Nerves (w/ electrical signals)
How does the stomach have different tissues working together?
Glandular tissue
secretes enzymes (protease) and acid- break down protein and sterilise the food from any bacteria
also secretes mucus- lines and protects the stomach from digesting itself
Muscular tissue
contracts- churns stomach and food within it
Outer epithelial tissue
covers outside of stomach- structural
Inner epithelial tissue
covers inside of stomach- structural and protects organ from digesting itself
What is digestion?
Macromolecules of food being physically and chemically broken down into more useful products (for growth, repair and energy)
What are the steps of digestion?
Mouth
food broken down physically w/ teeth
carbohydrase break up carbohydrates
Oesophagus
tube connecting mouth and stomach- food squeezed down
Stomach
acid and enzymes breaks food down chemically and physically
protease breaks up protein
Liver
stores sugar
produces bile
Pancreas
produces bile salts
produces enzymes for digestion
produces insulin
Small intestine
lipase breaks down fats
soluble food absorbed into the bloodstream
Large intestine
water absorbed into the bloodstream
What are the different layers of a leaf?
(bottom to top)
Guard cells
open and close to allow stomata gas exchange
Spongy mesophyll
provides short diffusion pathways
Palisade layer
main site of photosynthesis (lots of chloroplasts)
Waxy layer
waterproof
prevents evaporation and water loss
open and closes
What is a vascular bundle?
Xylem and phloem
what the plant uses to provide water ad sugars (circulatory system)
What is the function of xylem tissue?
Transporation
transports water
What is the function of phloem tissue?
Translocation
transports sugar
What are the features of xylem and phloem?
Xylem
transporation (water and minerals)
one-directional
dead, hollow cells
Phloem translocation (sugars/food) two-directional living cells contains sieve plates Active transport (use energy to transport sugar)
Where are xylem and phloem tissue found?
Roots and stems
What is the function of a root?
Absorbing water for the plant
What is the function of the stem?
Holds the plant together
Is a pathway for sugars and water to move around the plant
What is the function of the upper epidemis in a plant?
Prevents evapotransporation
What’s the equation for photosynthesis?
Carbon dioxide + water (+light +chlorophyll) –> Glucose + oxygen
What are the sugars made in photosynthesis used to make?
Proteins
Starch
Lipids
Cellulose
What are proteins in a plant made from?
Proteins= polypeptide chain of amino acids (made by ribosomes)
-Nitrogen (from soil) + glucose (from photosynthesis) = Amino acids
What is the starch in a plant made from?
Polysaccharide chain of aplha glucose molecules
What are lipids in a plant made from?
Gylcerol + 3 fatty acid chains
What is the cellulose in a plant made from?
Polysaccharide chain of beat glucose molecules
What are the features of a leaf?
Large SA
-traps as much light as possible
Side veins
-transporation & translocation
Thin and flat
-short diffusion pathways allow gas exchange
Chloroplasts (containing chlorophyll A & B, xanthia)
-photosynthesis (range of pigments absorb range of wave lengths)
Midrib
-keeps the structure of the leaf
What are the limiting factors that affect the rate of photosynthesis?
Concentration of carbon dioxide
Light intensity
Warmth/Temperature
What’s a ribosome?
A macromolecule that joins amino acids together to form a proteins
What is a protein?
Polypeptide chains of amino acids clamped together by ribosomes in cells. They are three dimensional globular shapes
What is an enzyme?
A three dimensional biological catalyst that speed up chemical reactions (anabolic or catabolic) in a cell
What is an anabolic reaction?
A reaction that builds something up
What is a catabolic reaction?
A reaction that breaks something down
What’s a substrate?
What a specific enzyme works on
How do enzymes work on their substrates?
Enzymes have specific active sites that fit in with their specific substrate. When they lock together to form an enzyme-substrate complex, they speed up the anabolic or catabloic reaction that’s already taking place. (lock&key theory)
What are some uses of enzymes?
Soft centre chocolate
-enzymes keep it soft
Biological washing powder
-enzymes included break down food stains
Baby food
-enzymes to break down food (already partially broken down) to assist undeveloped digestive system
Alcohol, bread and cheese production
-enzymes used for fermentation
Slimming bars
-include enzymes
What enzyme breaks down starch?
What is it broken down into?
Amylase
Glucose
What enzyme breaks down protein?
What is it broken down into?
Protease
Amino acids
What enzyme breaks down lipids?
What is it broken down into?
Lipase
Fatty acids and gylcerol
What is the role of bile salts in digestion?
Produced by the liver and released by the gall bladder into the small intestine, bile salts cause the emulsification of fats. This increases their surface area, which makes it quicker for enzymes (lipase) to break down the droplets of fat into soluble molecules.
What are fermentation tanks used for?
To grow a bacterial population in it’s specific optimum conditions
What the optimum conditions for bacterial growth?
~38 degrees
Controlled light levels (dependent on species)
Controlled oxygen levels (dependent on species)
Moisture
A growth medium
How is protease used in baby food?
The food is partially digested
-their digestive system isn’t developed enough to break down some macromolecules
BUT
-amino acids are crucial to their development
How is amylase used in food production?
Using cane sugar is expensive
-instead cheaper sources of carbohydrates are used
+ amylase= breaks down into glucose (sugar)
How is isomerase used in slimming bars?
Isomerase catalyses the changing of glucose to fructose
-fructose tastes sweeter for less calories & is cheaper
What qualities must industrial enzymes have?
Long shelf life
Thermally stable
Wider than usual PH tolerance
Work in the presence of chemicals that usually stop enzymes working
- Not easily denatured, Robust
What are the word and symbol equations for aerobic respiration?
Glucose + Oxygen –> Carbon dioxide + Water
C6H12O6 + 6O2 –> CO2 +H2O
What is the mitochondria in a cell?
Organelle- site of aerobic respiration
has a high surface area
What is glycogen?
Stores of sugar in muscles & granules in the liver
What happens if glycogen stores are full?
Glycogenasis turns into the production of fats
How does the body meet the increased energy demand brought on by exercise?
Increase of heart rate
Increase in breathing rate
–> to feed body w/ elevated levels of glucose and oxygen
What is the word equation for anaerobic respiration?
Glucose –> Lactic acid
Is anaerobic respiration reversible?
Yes
How do you reverse anaerobic respiration and convert lactic acid back to glucose
+ Oxygen
What is oxygen debt?
When a person is using more energy than they can sustain aerobically
–> body goes into anaerobic resp. to pay for it (- build up lactic acid–> needs to be paid back w/ oxygen at some point)
What are the two types of cell division?
Mitosis
Meiosis
Where does mitosis occur?
Normal somatic cells
What are somatic cells?
Body cells that aren’t gametes
Is mitosis a haploid or diploid process?
Diploid
Exact copies made
What is mitosis?
The cell division of somatic cells to produce diploid exact copies
Where does meiosis occur?
Gametes
What are gametes?
Sex cells
-Sperm & Eggs
Is meiosis a haploid or diploid process?
Haploid
What is meiosis?
The cell division of gametes to produce haploid cells
- The production of sex cells
Do organisms who reproduce asexually use mitosis or meiosis for cell division?
Mitosis
Define haploid
When one set of the chromosomes of the cell are conserved in cell division
(n)
Define diploid
When both sets of the chromosomes of the cell are conserved in cell division
(2n)
Give 4 examples of cells that go through mitosis
Red blood cells
Skin cells
Neurones
White blood cells
What is the process of mitotic cell division?
The DNA within the nucleus of a somatic cell replicates itself exactly
-The cell splits into 2 identical copies with the same genetic info.
What is the process of meiosis cell division?
The DNA within the nucleus of a gemete replicates itself
Swapping over- chromosomes will swap part of their DNA to ensure genetic variation
First division- cell divides into 2
Second division- those cells divide in 4 in total (2 each again)
= 4 X hapoloid gametes
Who was Mendel?
A Czechoslovakian monk who first presented gene theory after carrying out experiments on pea plants
What were Mendel’s experiments with pea plants?
Grew and tracked reproductive of 1000s of pea plants
Controlled the pollination
- Then tracked characteristics that were produced
–> Used mathematics to find the ratios of dominant and recessive genes
How did scientists rediscover Mendel’s work?
He published papers he had written of his findings for peer review
Define genes
Small units that code for a specific characteristics
Define alleles
Alternative characteristics in a gene that could be present
Define monohybrid inheritance
The tracking of one type of characteristic
When drawing Punnet squares, what do you always assume about the parents?
They are pure bred
What is the first generation of a Punnet square called?
First fillial generation
What is the second generation of a Punnet square called?
Second fillial generation
What are the forms that you can present the probability of a characteristic from a Punnet square?
Ratio
Percentage
How do you represent a dominant gene on a Punnet square?
With a capital letter
How do you represent a recessive gene on a Punnet square?
With a lower case letter
What does the word phenotype describe?
The observable physical characteristics of an organism
What does the word genotype describe?
The combination of alleles of an organism
the genetic make-up
Define homozygous
A pair of matching alleles
Define heterozygous
A non matching pair of alleles
-one dominant, one recessive
What is a dominant allele?
An allele that always shows, even if the individual only has 1 copy of it
(From one parent)
What is a recessive allele?
An allele that only shows if the individual has 2 copies of it
(From both parents)
Give 2 examples of recessive alleles
Allele for blue eyes
Faulty allele for cystic fibrosis
Give 2 examples of dominant alleles
Allele for brown eyes
Faulty allele for polydactyly
What is the chromosome pair that codes for a male offspring?
X + Y
What is the chromosome pair that codes for a female offspring
X + X
What are the chances of having a male offspring?
50%
What are the chances of having a female offspring?
50%
What do genes code for?
A particular protein
What is a gene?
A small section of DNA
What shape does DNA take?
A double helix
Describe DNA
A double helix with a sugar phosphate backbone that contains organic base pairs
What are chromosomes made up of?
DNA
What are the organic base pairs that make up DNA?
Adenine and Thymine
(A & T)
Guanine and Cytosine
(G & C)
What is the human genome made up of?
23 pairs of chromosomes
What is the central dogma of genetics?
DNA –> RNA –> Protein
Describe the process of protein synthesis
DNA unzips itself to make mRNA (u replaces t)
Codons fit w/ anti-codons to form amino acids
Ribosomes clamp AA together to form polypeptide chain of protein
What is cystic fibrosis?
A relatively common genetic disorder
- affects cell membrane in the lungs & digestive system
- -> Produces too much thick mucus
What is cystic fibrosis caused by?
A faulty recessive gene
noth parents need to be carriers or sufferers
What are the odds of someone being a carrier of cystic fibrosis if both their parents carry the gene?
50%
What are the odds of someone being a carrier of cystic fibrosis is both their parents carry the gene?
25%
What are the odds of someone being a carrier or a sufferer of cystic fibrosis if only one of their parents carries the gene?
0%
What are some of the symptoms of cystic fibrosis?
Lung problems:
chest infections, inflammation of airways, shortness of breath
Digestive system problems:
severe bowel obstruction, jaundice, malnutrition, diabetes
weakened bones, difficulty with fertility,liver problems
Is there currently treatment for cystic fibrosis?
No
-possible to control symptoms
How does cystic fibrosis affect people’s daily lives?
Daily care
-some can’t attend school/work
Most men are infertile
Most women find it hard to have kids
What is the test for cystic fibrosis?
Blood sample from mother’s womb during pregnancy
What is polydactyly?
Genetic disorder resulting in extra digits being present on the hands or the feet
What causes polydactyly?
A faulty dominant allele
What is the chance of someone having polydactyly if one of the parents has it?
50%
What is the chance of someone having polydactyly if both of the parents have it?
75%
What is the treatment for polydactyly?
If not fully formed- no bone:
Vascular clip attached to base- stops blood flow- digit falls off
If more formed- w/ bone:
Surgery- amputation and reconnecting systems so that the hand/foot is fully functioning
What is the test for polydactyly?
Sometimes seen on prenatal ultrasounds
-evident at birth
X-rays taken after birth to see how formed the digit is- (bone or not)
How does polydactyly affect people’s every life?
Not much- most have extra digit removed early on
What is embryo screening?
Taking blood from an embryo and screening it to see if it has any faulty alleles for genetic disorders such as cystic fibrosis
What are the ethical arguments for and against embryo screening?
For
Gives parents an element of choice for how they want to proceed, knowing the embryo carries the faulty allele
Against Expensive If doctors mess it up- parents may not realise Can only provide single screening Messing with embryos- against God's will
What are the ethical arguments for and against DNA screening?
For
Less invasive than a blood sample
Can lead to reliable convictions
Can be pivotal in the reversal of wrong convictions
Can be used to protect those wrongly accused of crimes
Against Lack of privacy- trust in government Data could be hacked (identity thieves) Could easily be manipulated -(corrupt states)
What are the ethical arguments for and against stem cell research?
For
Could be used to further scientific knowledge
Can lead to better understanding and treatment of diseases (such as Parkinson’s)
Could eventually replace transplants
-(much lower risk of rejection)
Against
Ends potential lives
Goes against God’s will- MURDER
Funding is limited
What are the stages of evolution?
Every population has genetic variation -variation of characteristics Habitats provide selection pressure Survival advantage -SURVIVAL OF THE FITTEST Genes passed on through reproduction
Define a selection pressure
Things that result in a change of something
What causes new species to form?
Selection pressures
What are some examples of selection pressures?
Change in food
Change in temperature
New predators
What will geographical isolation result in?
New selection pressures
–> Formation of new species
What is the best source of evidence we have for evolution?
Fossils
Define a fossil
Imprints or impressions of a once living organism that has formed over millions of years
-The organic part has been replaced by rock minerals
What will happen to a fossilised organism if one or more of the conditions for decay are missing?
What is an example of this?
Part of the organism might not have decayed
Fossilised amber
-(not true fossil- not replaced by rock minerals)
What are some examples of preservation?
Drying
Freeze-drying
Oxygen removal
Why can anything be preserved if oxygen is removed?
The growth of bacteria relies on the presence of oxygen
-no oxygen=no bacteria=no decay
How do fossils form?
An organism dies- falls to the bottom of the sea
Layers of sediment trap it on seabed over time
Layers are compact –> low levels of oxygen- decomposition is slow
Microbes slowly decompose organic material
Organic material is replaced w/ rock minerals
–> causing impression in the rock over millions of years
