Biology Salters Nuffield
Edexcel A Level: Topic 4
QUESTIONS WITH ANSWERS
SOLVED.
3 phase testing of drugs on humans - CORRECT ANSWER✅✅1. healthy, small
sample to test for side effects, low concentrations to measure tolerance, ill people not
used because they could potentially become more ill
2. small number of patients, measuring efficacy - how well the drug works at lowest
concentrations possible
3. large group of patients - efficacy and value in comparison to current 'best' treatments
in clinical practices
- multicentre trials to allow generalisability
5 agents of evolutionary change - CORRECT ANSWER✅✅mutation, gene flow, non-
random mating, genetic drift, natural selection
adaptation - CORRECT ANSWER✅✅a characteristic that enables an organism to
survive and reproduce and pass on their trait
adaptations of xylem - CORRECT ANSWER✅✅dead cells - continuous column, no
energy requirement or organelles
narrow tubes - don't break easily
pits allow movement of substances in and out
lignin strengthens xylem, allows walls to stretch at first for cell elongation
alpha glucose structure - CORRECT ANSWER✅✅OH on bottom
anatomy vs physiology - CORRECT ANSWER✅✅structures such as bone, teeth, fur
physiology - metabolic processes e.g. digestion, hybernation
animal conservation - CORRECT ANSWER✅✅zoos - breeding programmes - aim to
increase population size, create greater genetic diversity, sperm and eggs/animals
moved between zoos, selectively breed the most genetically different animals, use a
stud book / DNA profiling
reintroduction to the wild - zoos must ensure animals show appropriate behaviour when
released, protect against poaching/hunting, establish a suitable habitat for
reintroduction, educate on the importance of rare species
, aseptic techniques - CORRECT ANSWER✅✅- flaming
- updraft
- 45deg angle to open petri dish
- disinfectant - Virkon
- tape in a X shape to avoid anaerobic conditions
- Incubate at 25deg C - lower than human body temp to avoid optimum temp for
pathogens
- autoclave to sterilise the equipment before and after
beta glucose structure - CORRECT ANSWER✅✅OH on top
biodegradable definition - CORRECT ANSWER✅✅can be broken down by biological
processes such as by decomposers or sunlight
biodiversity definition - CORRECT ANSWER✅✅a measure of how varied an
ecosystem is, in terms of genes, species and habitats in an area
biodiversity hotspots - CORRECT ANSWER✅✅A relatively small area, such as an
island with high biodiversity and an exceptional concentration of endemic species, also
threatened with destruction
bioplastics - CORRECT ANSWER✅✅biodegradable and recyclable plastic derived
from biological substances (polyactide) from starch derived from corn syrup, rather than
petroleum (fossil fuel) - sustainable and renewable
Calcium ions - purpose in plants and symptoms of deficiency - CORRECT
ANSWER✅✅- calcium pectate in cell wall formation
- short and weak, stem floppy, dead regions on leaf where cell wall formation is
incomplete
cell elongation - CORRECT ANSWER✅✅= the process by which water is added to the
cell to create more cytoplasm and turgor pressure to push against the cell wall and
increase cell size
primary cell wall can be elongated until fully formed
cell wall formation - CORRECT ANSWER✅✅cellulose fibres deposited
hemicellulose entangles and calcium pectate glues
mesh-like structure to create a strong matrix
cell wall structure and function - CORRECT ANSWER✅✅- made of cellulose (since
sugars are more readily available in plants than proteins which require nitrates)
- fully permeable because of pits in the cell wall
- plasmodesmata are pores allowing cells to connect to transport substences between
them
Edexcel A Level: Topic 4
QUESTIONS WITH ANSWERS
SOLVED.
3 phase testing of drugs on humans - CORRECT ANSWER✅✅1. healthy, small
sample to test for side effects, low concentrations to measure tolerance, ill people not
used because they could potentially become more ill
2. small number of patients, measuring efficacy - how well the drug works at lowest
concentrations possible
3. large group of patients - efficacy and value in comparison to current 'best' treatments
in clinical practices
- multicentre trials to allow generalisability
5 agents of evolutionary change - CORRECT ANSWER✅✅mutation, gene flow, non-
random mating, genetic drift, natural selection
adaptation - CORRECT ANSWER✅✅a characteristic that enables an organism to
survive and reproduce and pass on their trait
adaptations of xylem - CORRECT ANSWER✅✅dead cells - continuous column, no
energy requirement or organelles
narrow tubes - don't break easily
pits allow movement of substances in and out
lignin strengthens xylem, allows walls to stretch at first for cell elongation
alpha glucose structure - CORRECT ANSWER✅✅OH on bottom
anatomy vs physiology - CORRECT ANSWER✅✅structures such as bone, teeth, fur
physiology - metabolic processes e.g. digestion, hybernation
animal conservation - CORRECT ANSWER✅✅zoos - breeding programmes - aim to
increase population size, create greater genetic diversity, sperm and eggs/animals
moved between zoos, selectively breed the most genetically different animals, use a
stud book / DNA profiling
reintroduction to the wild - zoos must ensure animals show appropriate behaviour when
released, protect against poaching/hunting, establish a suitable habitat for
reintroduction, educate on the importance of rare species
, aseptic techniques - CORRECT ANSWER✅✅- flaming
- updraft
- 45deg angle to open petri dish
- disinfectant - Virkon
- tape in a X shape to avoid anaerobic conditions
- Incubate at 25deg C - lower than human body temp to avoid optimum temp for
pathogens
- autoclave to sterilise the equipment before and after
beta glucose structure - CORRECT ANSWER✅✅OH on top
biodegradable definition - CORRECT ANSWER✅✅can be broken down by biological
processes such as by decomposers or sunlight
biodiversity definition - CORRECT ANSWER✅✅a measure of how varied an
ecosystem is, in terms of genes, species and habitats in an area
biodiversity hotspots - CORRECT ANSWER✅✅A relatively small area, such as an
island with high biodiversity and an exceptional concentration of endemic species, also
threatened with destruction
bioplastics - CORRECT ANSWER✅✅biodegradable and recyclable plastic derived
from biological substances (polyactide) from starch derived from corn syrup, rather than
petroleum (fossil fuel) - sustainable and renewable
Calcium ions - purpose in plants and symptoms of deficiency - CORRECT
ANSWER✅✅- calcium pectate in cell wall formation
- short and weak, stem floppy, dead regions on leaf where cell wall formation is
incomplete
cell elongation - CORRECT ANSWER✅✅= the process by which water is added to the
cell to create more cytoplasm and turgor pressure to push against the cell wall and
increase cell size
primary cell wall can be elongated until fully formed
cell wall formation - CORRECT ANSWER✅✅cellulose fibres deposited
hemicellulose entangles and calcium pectate glues
mesh-like structure to create a strong matrix
cell wall structure and function - CORRECT ANSWER✅✅- made of cellulose (since
sugars are more readily available in plants than proteins which require nitrates)
- fully permeable because of pits in the cell wall
- plasmodesmata are pores allowing cells to connect to transport substences between
them
