PPQs Flashcards
(28 cards)
Which feature is associated with a prokaryotic cell?
A - cell walls made of chitin
B - extrachromosomal DNA that is circular
C - linear DNA that can form plasmids
D - 70S ribosomes present in Endoplasmic reticulum
B
Which elements are present in an amino acid?
C H O N
Description of glucose molecules in terms of C and OH groups:
Contains 5 OH groups and has a C:O ratio of 1:1
What reduces uncertainty in measuring?
High resolution
Low uncertainty / percentage error
Fewer random measurements errors
Fewer uses/ measurements required
How does an enzyme increase rate of breakdown?
Bonds in substrate are put under strain so activiation energy is lowered
How to calculate percentage error
Error/ measurement X 100
What do different RF values say about different substance R group?
Different polarity / charge / functional group
Roles of cell surface membrane:
Barrier between cell and environment
Regulates which substances enter and exit cell
Site of chemical reactions
Cell signalling
How does cholesterol affect fluidity?
Tempurature must be known to conclude the effect of cholesterol
At low temperatures, it increases fluidity
At high temperatures it decreases fluidity
Other factors affect fluidity e.g concentration of saturated and unsaturated fatty acids, presence of solvent
Why do larger organism like bird need a circulatory system but smaller organisms do not?
High metabolic demand because high activity levels
Smaller SA:V means diffusion pathway is too long for transport of substances, not efficient enough for supply of e.g oxygen
How do proteins affect cells and whole organisms?
Changes proteins inside cell
Effects outside of cell
Increased activity requires more energy
More respiration, rate of respiration increases to supply ATP
Outline how different properties of glucose, starch and glycogen relate to their function in cells.
Glucose is soluble and polar because it has chemical energy in its bonds, it is a respiratory substrate / source of energy
Starch and glycogen are insoluable and compact. They have a larger SA used for energy storage and allows quick release of energy (glucose)
Glycogen is broken down faster than starch due to a higher SA and many branched ends
How does meiosis produce genetic variation in the offspring
Crossing over in prophase 1
Independent assortment of chromasomes in metaphase 1
Independent assortment of chromatids in metaphase 2
DNA/ gene mutation
How can vaccinations programmes prevent epidemics?
Mass vaccination at the start of an epidemic can prevent spread of pathogen
Herd immunity
Minimises possibility of another outbreak of the disease spreading
How to use Colourimeter?
Calibrate Colourimeter with distilled water
Add red filter
Place samples in a cuvette
Place range of known glucose concentrations
Measure percentage transmission / light absorption of glucose samples
Describe carrying out chemical tests for lipids and starch, include apparatus and reagents and results you would expect.
Lipids:
Apparatus: test tube, filter paper and funnel, pipettes
Emulstion test:
Add test solution to ethanol, mix with water, filter and add water to filtrate
Result - clear to cloudy
Starch:
Apparatus: test tube, pipette
Add a few drops of iodine to the test solution
Brown - dark blue
Outline the structure and function of a phloem tissue in the stem of a plant
Function:
Sieve tube elements:
- translocation
- transport of solutes / assimilates
- tissue ,ade up of sieve tube elements and companion cells
- allows mass flow up and down plant (from source to sink)
- assimilates used in respiration
Companion cells:
- support to siev tube elements
- gains sucrose by active transport
- allows loading of sucrose, solutes to sieve tube elements
Stucture:
Sieve tube elements:
- living cells
- long hollow continuous tubes
- stacked end to end to allow mass flow
- no nucleus/ few organelles
- sieve pores to allow solutes passing through and linking cytoplasms or adjeacent cells
Companion cells:
- dense cytoplasm with lots of mitochondria
- large nucleus
Why do large multicellular plants need a transport system but small multicellular plants do not?
SA:V ratio is smaller so diffusion distance is longer so diffusion is too slow so assimilates / nutrients are unable to reach inner cells quickly
Greater metabolic demand
When does the semi lunar valve open?
When aortic pressure is below ventricular pressure
What is precision and what is accuracy?
Results having a small standard deviation is precision
Accuracy is mean result being close to a comparable value
What is the correct cofactor for carbonic anhydrase?
Zn2+
What feature is common in bacterium, Protoctista and fungus?
Ribosome
Outline the steps involved in the process of making modified polypeptides.
Modified gene undergoes transcription in nucleus
Production of modified mRNA
MRNA leaves nucleus and goes to ribosomes where it is translated
TRNA with specific amino acids binds its anticodon to codon on mRNA
Formation of peptide bonds between amino acids
Name and define three types of biodiversity:
Genetic biodiversity: different versions of alleles within a species
Species biodiversity: species richness and evenness of a species. Or the number of species in an ecosystem
Habitat biodiversity: number of different habitats/ range of different habitats in an ecosystem
