questions ive got wrong Flashcards
when adding volumes of acid to a suspension when looking at how changing pH affects the activity of pepsin, what can be done to increase validity ?
ensure that there is an equal volume in each tube
how does repeating the test improve the investigation
-improves reliability so it can assess the spread of results ( standard deviation) allows for calculating the mean
why are controls carried out
- to compare the effect of any other treatments/ changed conditions
for measuring why is a capillary tube better than a graduated pipette
-capillary tube is smaller than a gas syringe (smaller diameter) so less uncertainty- finer graduations
how to increase validity in a practical examples
- take more intermediate times as unexpected change could occur.
- use a better piece of apparatus e.g using a spreader for evenness
- labelling things not to get confused
- using a wider range of variables e.g temp
applications of adult stem cell cloning
- development and treatment of disease
- preserve endangered organisms
- able to produce organs
why are lipids better storage molecules than carbohydrates
- have more c-c bonds and more c-h bonds
- contain more energy per molecule
- they are also insoluble and don’t affect water pot of a cell
how does adrenaline bind to cardiac cells
binds to a receptor in the cell surface membrane which is a glycoprotein
suggest why reduced heart rate is sometimes seen in people who are very aerobically fit
- they have an increased stroke volume, increased strength/ thickness of heart muscle
does lymph and tissue fluid contain neutrophils
yep
tow advantages of keeping blood inside vessels
- blood can move at high pressures
- increases rate of flow-> blood can move quicker
how does the artery withstand pressure
- outer layer= collagen
- provides strength
- walls will not tear , no damage to endothelium
how does the artery maintain pressure
- elastic fibers /elastic tissue to allow for recoil
- smooth muscle which constricts lumen/ artery
why is the left ventricle thicker than the right ventricle
- more muscle to create more force
- needs to create a higher pressure
- pushes blood against greater resistance
- left ventricle pushes blood further (supplies systemic system)
what does a TEM allow for
smaller organelles to be identified (ribosomes e.g)
whats the parasite that causes malaria
plasmodium
name the vector for the malarial parasite
female anopoles
describe the action of the B lymphocytes in the immune response
B lymphocyte= the humoral response
- B cell/ lymphocyte has antigen receptor/ carries an antibody on its surface, its specific to only 1 antigen. clonal selection occurs which is the activation of specific b lymphocyte/ cell by macrophages/ antigen presenting cells / T-helpers / cytokines / interleukins
- clonal expansion occurs -> selected cell divides by mitosis.
- b- cell differentiates to plasma cell and memory cells.
- memory cells= long lived and remain in the body, it provides the secondary response-> faster response to subsequent exposure
3 reasons why vaccine for malaria is difficult
- parasite hides in RBCs
- more than one stage so diff stages ahve diff antigens
- many diff strains of plasmodium
how does fossil evidence show evolution
-shows how organisms have changed over time
-
how does fossil evidence show evolution
- shows how organisms have changed over time
- fossils can be dated
- fossils show intermediate forms
two causes of variation
- mutation
- environment
characteristics of continuous variation
- caused by many alleles and environment
- no defined activities
- quantitive
- range of values
benefits of antibiotics
- reduces disease
- prevents gut problems
whats adhesion
the attraction of water molecules to the impermeable walls of the xylem tissue
why is sucrose transported through a plant rather than a carbohydrate
because its soluble in water and is not used up during transport, it is only removed at a sink
how is transport in the phloem and xylem simmilar
- both involve mass flow
- both carry solutes in solution
how is transport in the phloem and xylem different
transport in the phloem can move up and down but in the xylem, substances can only move up
Describe two features of the circulatory system that could affect blood pressure.
- a narrower lumen would increase blood pressure
- force of ventricular contraction
- strength of elastic recoil
when talking abt having confidence in results, what does this mean
Confidence is a qualitative judgement expressing the extent to which a conclusion is justified by the quality of the
evidence.
(i) State ways a student could have ensured they had confidence in their results.
- repeat readings
- calc mean
- identify anomalies
In humans, a circulatory system is needed to transport substances around the body by mass transport.
Explain why humans need a mass transport system
humans are large and have a low sa:vol ratio. there is a long diffusion distance so without mass flow, substances wouldn’t be supplied quickly enough
Suggest why a hole in the septum is open in the fetus before birth.
-lungs not functioning rn, the fetus isn’t breathing, blood isnt oxygenated in the lungs but it is in the placenta
what are the bonds in the tertiary structure
folding is caused by:
-ionic bonding, disulphide bonding, hydrophilic and phobic interactions
what type of binding occurs in haemoglobin
reversible binding
what is meant by tertiary structure
- further folding of the secondary structure into a 3d shape
- caused by ionic bonding, disulphide bonding, hydrophilic and phobic interactions
can diffusion occur in aretries
no cu arteries have thick walls
what is the bhor effect
…
Describe the role of haemoglobin in transporting oxygen around the body.
ocygen has a high affinity for 02
oxygen binds to haemoglobin in lungs/ alveoli/ high po2. oxyhaemoglobin is formed
oxygen relased in tissues/ whwere needed
what could u do to see if two species are related or not
- breed the two species together to see if fertile offspring has been produced, if fertile offspring has been produced, they are the same species
how can u tell how old fossils are
fossils deeper in the ground are older than those near the surface
Explain how biological molecules can provide evidence that species have evolved
DNA:
if two species has a similarity in order of base sequences, this implies an evolutionary relationship.
Cytochrome C:
if species have a simmilar in order of amino acids/ primary structure, this implies evolutionary relationship
give features of continuous variation
- range of values/ intermediates
- influenced by the environment
- influenced by more than 2 genes
three reasons why the three-domain classification system is now used in preference to the fivekingdom system
- bacteria and archaea ahve fundamental differences
- 3 domains for phylogeny fit better, reflects evolutionary relationship better.
- all eukaryotes have a nucleus
- bacteria and archaea have different cell membranes/ flagella
Define the term phylogeny and explain how phylogeny is related to classification
- phylogeny is the study of evolutionary relationships between organisms.
- phylogeny is the basis of classification
- molecular evidence such as DNA and cytochrome C is used to classify
- species within the same group have shared phylogeny/ a common ancestor
Outline three reasons why it is important to conserve the Iberian lynx.
- aesthetics, they are nice to look at
- tourism- might provide a useful resource
- impact on food chain if lost
The type
of variation that is caused by differences in DNA is known as…
genetic variation
Fossils provide strong evidence that organisms have evolved over time.
Describe other types of evidence that support the theory of evolution.
- DNA
- Cytochrome C
- comparison of morphology and physiology
- evolution seen within human history
State the name given to the evolution of a new species.
speciation
differences between electron microscopes and laser scanning
LSCM has a lower resolution
what happens at metaphase 1
independent assortment
talk abt the xylem thickness in hydrophytes
thinner walls, less xylem
talk abt the xylem thickness in xerophytes
thicker, more walls
similarity between xylem and phloem
-both are made of cells joined end to end
difference between xylem and phloem
phloem= no bordered pits , xylem= bordered pits
-lignified walls
fish dissection
-remove operculum and obtain gills, put underwater to see structure clearly
mammal trachea vs insect
- mammal= much wider diameter
- has c shaped cartilage while insects dont
- mammal= smooth muscle, goblet and ciliated and insect dont
how alveoli are adapted to efficient gas exchange extras
- surfactant- prevents alveoli from collapse
- elastic fibres- for stretch and recoil
- internal gas exchange surface so rate of diffusion is constant
what forms plasma cell clones
b-cells
why is the primary response delayed
- due to clonal selection and clonal expansion
why would a woodland be more biodiverse than a farm
- lack of monoculture
- no pesticide use
- mor food types available
one cat is a diff colour to another, whats this called
genetic biodiversity
when writing out how to carry out a test what do u need to state
-a control variable
