Paper 1 questions Flashcards
(28 cards)
Describe how mineral ions are taken up by root hair cells. (3)
(mineral ions) are taken up by active transport (1)
* through carrier proteins (1)
* this requires {energy / ATP} (1)
Explain why a diet based on plant protein produces lower greenhouse gas emissions than a diet based on animal protein.
- because plants produce {organic compounds/biomass} from photosynthesis (1)
- plants remove carbon dioxide (from the atmosphere) (1)
- because animals produce (more) carbon dioxide by respiration (1)
- because (some) animals produce methane (1)
Name the plant organelle that fixes carbon dioxide from the atmosphere
Chloroplast
Net primary productivity (NPP) is a measure of the increase in biomass of a plant.
Explain why respiration affects the production of biomass.
GPP – R = NPP (1)
{organic molecules / glucose} used in respiration to provide energy (1)
because the more {organic molecules / glucose } used in respiration, the less is available for the production of biomass
The quantity of extracted DNA is amplified using
A DNA profiling
B polymerase chain reaction
C RNA profiling
D translation chain reaction
B polymerase chain reaction
Devise a procedure, using electrophoresis, to compare the amplified DNA from these two types of human.
restriction { enzymes / endonucleases } used to cut DNA (from modern humans and Neanderthals) into fragments (1)
* DNA samples are loaded onto (agarose) gel (1)
* {electric current is passed through / potential difference is applied across} the gel (1)
* markers are added to visualise the bands (1)
* the position of the bands produced can be compared (1)
Give the meaning of the term totipotent cell
- a cell that has the ability to differentiate (1)
- into all cell types (1)
Describe how cells become specialised.
- (chemical) signals cause some genes to be {activated/switched
on} (1) - only activated genes {are transcribed / produce mRNA} (1)
- (mRNA leads to) synthesis of specific proteins which cause
cell modification (1)
Explain how epigenetic changes affect the development of tissues in the embryo.
- DNA (in a chromosome) is wrapped around histones (1)
- {acetylation / modification} of the histone affects {binding of
RNA polymerase / chromosome unwinding} (1) - methylation of DNA affects { transcription of genes /
production of mRNA } (1) - therefore gene expression is altered (1)
State what is meant by the term habitat.
- the area inhabited by a particular { species / organism } (1)
(a) Describe the structure of the cell surface membrane
- cell membrane is (mainly) phospholipids and protein (1)
- phospholipids form a bilayer (1)
- proteins float in the phospholipids / change position / fluid
mosaic model (1) - proteins may span the bilayer or be located in only one
layer (1)
Does the phloem or xylem contain lignin?
Only the xylem contains lignin
Explain why the production of fibres from nettles is more sustainable than fibres
produced from crude oil.
- nettle plants can be grown so they are renewable (1)
- (crude) oil (is non-renewable and) will run out (1)
- use of fibres from nettles will be available to future generations (1)
- clothing made of nettle fibres is biodegradable (1)
Explain why the pH would change after lipase hydrolyses lipids
Glycerol and fatty acids produced when lipids are hydrolysed
Fatty acids will cause pH to decrease
Explain why the value for GPP is lower than the light energy available to the ecosystem.
- not all of the light falls on the { leaves / plants / producers }
(1) - some of the light is reflected (from the surface of the leaf) (1)
- some of the light misses the chloroplasts (and passes through leaf) (1)
- some of the light is { the wrong wavelength / not absorbed by the chlorophyll } (1)
State what is meant by the term species.
a group of organisms that can interbreed to produce fertile
offspring
Describe how DNA profiling could be carried out to show that these snakes are
different species.
- DNA obtained from the two types of grass snake (1)
- { PCR / restriction enzymes } used to produce fragments of DNA (1)
- gel electrophoresis used to analyse the DNA samples (1)
- (gel electrophoresis) used to separate the fragments of DNA (1)
- more differences in the pattern of bands produced would indicate that the snakes are different species (1)
Explain why enzymes that are incorrectly folded cannot carry out their function.
- (if the protein is not folded correctly) the {tertiary structure / 3D shape} would be different (1)
- therefore the active site of the enzyme would not { fit / bind with } the substrate / it would not be able to form an enzyme substrate complex (1)
- therefore it would not be able to catalyse the reaction (1)
State what is meant by the term endemic.
found only in one geographical location (1)
Explain why the presence of microorganisms on the skin and in the gut helps to
prevent pathogenic organisms multiplying in the body
- flora in the gut and skin are better adapted to the conditions (1)
- therefore they can outcompete
pathogenic organisms (1) - bacteria in the gut secrete {chemicals /lactic acid} which help to destroy pathogens (1)
Describe how the pre‑mRNA may be modified before being translated on the ribosome.
- pre mRNA contains exons and introns (1)
- introns are removed and exons are spliced together (to produce a strand of mRNA) (1)
Explain why modification of pre‑mRNA enables one gene to give rise to more than one protein.
- the {exons can be spliced together in a different order / different exons can be removed } (1)
- therefore producing different sequences of amino acids (1)
A sperm cell contains a specialised lysosome called the acrosome.
Describe the role of the acrosome in fertilisation.
- it fuses with the cell (surface) membrane of the sperm cell (1)
- (digestive) enzymes are released (1)
- to break down the zona pellucida (1)
What is species richness?
The number of different species in one area
