B2 - Exam Mistakes Flashcards
Where is DNA found?
Nucleus of the cell
In the chromosomes
What is the function of a muscle cell?
To contract and relax
What is cardiac output?
Heart rate * stroke volume (amount of blood pumped in one pump)
Why do fit people have a lower heart rate?
They have a larger stroke volume meaning the cardiac output is the same but the heart doesn’t have to work as hard because the heart rate is lower
Give 5 ways that plants use glucose
Energy Starch Protein Fats Cellulose
What does fat break down into?
Fatty acids and glycerol
Why does digesting fat decrease the pH?
Fatty acids are produced which are of course acidic
What causes the daughter cells of mitosis to be genetically identical?
The DNA is replicated to make the daughter cells
If a person has polydactyly, what is the smallest number of alleles for polydactyly that could be found in the person and why?
1
Dominant allele
Someone has cystic fibrosis. How many copies of CF allele would they need to have CF and why?
2
Recessive allele
What is the function of mitochondria? 2 marks
To transfer energy for use
By aerobic respiration
Explain why someone with a higher cardiac output can run faster. 5 marks
They send more blood to the muscles
Which supplies more oxygen
And more glucose
So faster rate of respiration
Removes more carbon dioxide and lactic acid
How do plants get energy? 2 marks
Light is absorbed
By chlorophyll in the chlotoplasts
Why did Mendel think that the production of a large amount of offspring plants improved the investigation? 3 marks
Fertilisation is random
More likely to get theoretical ratios
Anomalies have a reduced effect
Why did people not support Mendel’s ideas? 3 marks
Didn’t know about chromosomes, DNA or genes
Mendel was not part of an academic establishment
He only worked on pea plants
Why is there no difference in the effect of pepsin after pH 5? 2 marks
Pepsin denatured
ENZYME no longer fits substrate
What are the 3 main ways that animals use diffusion?
For gas exchange because of respiration (oxygen in and carbon dioxide out)
Food molecules absorbed like glucose and amino acids
Water absorption in the large intestine
What are the 4 main ways that plants use diffusion?
Gas exchange because of photosynthesis (carbon dioxide in and oxygen out)
Water lost from leaves (transpiration)
Water absorption by roots
Mineral ions absorbed by roots
What is an allele?
One form of a gene
What does recessive mean?
Not expressed if dominant allele is present
Many early life forms were soft bodied. Why does this makes it difficult to be certain what these life forms were like? 2 marks
Fossils destroyed
Due to soft parts decaying
What is diffusion? 2 marks
Movement of molecules
From high to low concentration
What substance diffuses out of leaves through the stomata?
Oxygen
Describe how someone should decide where to place quadrats to investigate a distribution. 2 marks
Choose places randomly
Because it is the method of obtaining randomness
What is mechanical breakdown?
Breakdown of food due to muscles contracting (mouth and stomach)
Explain how a changed in the DNA of a gene can result in the production of an enzyme by that genre that won’t work. 3 marks
Sequence of amino acids is different
So the enzyme has the wrong shape
So the substrate will not fit into the enzyme
Where do you put the quadrat when measuring the distribution of an organism along a transfer and why?
At regular intervals down the transect
So that you can see how the distribution changes as you go along the transect
How many chromosomes are there in an adult cell?
46 (23 pairs)
What does isomerase do?
Turns glucose into fructose
How does a chromosome become 2 strands?
DNA replication
Explain why each chromosome must become 2 strands before the cell divides. 2 marks
One copy of each strand to each offspring cell
Each offspring cell receives the same genetic material
What could be done to ensure that a lamp used to change light intensity won’t affect temperature?
Heat bath before hand
Use LED instead
Explain how oxygen passes from the blood to the mitochondria of cells. 3 marks
Diffusion
From high to low concentration of oxygen
Through cell membrane
Suggest how receiving more sunlight could result in more flowers per stalk. 2 marks
More glucose / energy available because of more photosynthesis
So more growth of flowers possible
What is a dominant allele?
Expressed even when a different allele is also present
What is a recessive allele?
When a dominant allele is also present, it is not expressed
Only expressed if there are no other different alleles present
Why would scientists use stem cells when treating a damaged part of the brain. 2 marks
Stem cells can DIFFERENTIATE
To form brain cells
Describe how speciation occurs. 4 marks
Population is separated into 2 areas with different conditions
Mutations occur in the isolated populations
Natural selection acts differently on the 2 populations because of difference in conditions
Eventually the populations become so different that they can’t interbreed to produce fertile offspring anymore
Explain why the boy didn’t get the generic disorder. 2 marks
Also inherited normal gene from other parent
The changed gene was recessive and the normal one was dominant so normal one is expressed
Give 2 advantages of using immobilised isomerase in beads when making fructose
Isomerase will not contaminate fructose
Continuous flow process possible
Why is fructose used in slimming foods. 2 marks
Less fructose to get same sweetness
Less sugar means it is less fattening
Why do offspring plants from parents with different amounts of chromosomes not have the ability to reproduce sexually. 2 marks
Some chromosomes can’t pair up
There are gametes with extra genes
Why would it help a plant to survive if air was provided to it? 3 marks
Provides oxygen
For aerobic respiration
Supplying energy for survival
How could people improve validity when measuring distribution with transects? 2 marks
Repeat several times
Elsewhere along shore [parallel to original line]
