Unit 1
Describe the structure of cellulose
Beta glucose
Linear/ 1-4 glycosidic bonds
H-bonds between chains
State the area on an enzyme where the substrate binds
Active site
State which hormone is released to increase blood glucose
Glucagon
State two examples of mutualistic relationships
Zooxanthellae and coral
Mycorrhizae and orchids
Nitrogen-fixing bacteria and legumes
Outline the roles of two enzymes involved in DNA replication
Helicase unwinds DNA and breaks H bonds
DNA polymerase adds new nucleotides and forms phosphodiester bonds between them
Outline what a substitution mutation is
Nucleotide/ base is changed
State the name of the hormone that controls our circadian rhythm
Outline the advantages of the physical properties of water for aquatic animals
High specific heat capacity so temperature is stable
High buoyancy so expend less energy maintaining depth
State the word equation for aerobic respiration
Glucose + oxygen = Carbon dioxide + water
Outline the adaptations of the xylem vessel for transport of water
No cell walls
Lignin in walls to withstand tension
Pits for entry/ exit of water
Using examples, outline how different plants are adapted to obtain light in the forest canopy
Emergents grow very fast to reach above canopy
Lianas climb trees
Epiphytes land in trees higher up
Forest floor shrubs have large leaves/ wide range of pigments
If an mRNA sequence is:
AGGCCGAUUGCG
What was the DNA sequence on the sense strand?
AGGCCGATTGCG
Distinguish between incomplete dominance and codominance
Incomplete is where phenotype is a blend (e.g pink flowers)
Codominane is where both phenotypes are expressed (e.g. red and white petals)
HIV attacks helper T cells
When numbers are too low then a person cannot fight infections
Water potential higher inside plant cell
Water leaves
Plant cell shrinks
Plasmolyses
Outline the structure of ATP
Nucleotide
Adenine base
Ribose sugar
Three phosphate groups
Arteries have thick muscular wall
Small lumen
Veins have thinner wall/ less muscular
Large lumen
Valves
Describe the conditions required for coral reef formation
Shallow water
Warm temps
Slightly alkaline pH
Clear water
High salinity
State where the first tRNA binds in the ribosome to start translation
P-site
The gene for attached ear lobes is recessive. If a female with attached ear lobes has a baby with a man who is a heterozygote, what is the probability that their child will also have attached ear lobes?
50%
Outline how a signal is transferred from one neuron to another
Synapse
Neurotransmitters are released from presynaptic neuron
Bind to receptors on postsynaptic neuron
Open Na channels and depolarise
Distinguish between active transport and facilitated diffusion
Active transport requires energy
Moves substances against concentration gradient
Via carrier protein
Facilitated diffusion is passive
Moves substances along concentration gradient
Via channel protein
Describe the absorbance spectrum for chlorophyll a
High at ~450nm and ~600nm
Low between 500-600nm
Describe what happens during inhalation
Diaphragm contracts
External intercostals contract
Ribs move up and out
Volume in thorax increases/ pressure decreases
Air moves in
Distinguish between a fundamental and realized niche
Fundamental niche is theoretical based on zones of tolerance and adaptations
Realized niche factors in competition with other species
Outline the consequences of non-disjunction
Some gametes have two copies of a chromosome and some have no copies
Zygote would have trisomy (three copies) or monosomy (one copy) of a chromosome
Outline the role of hormones in the follicular phase of the menstrual cycle
FSH is maturing egg follicle
Estradiol is repairing uterine lining
LH triggers ovulation
Outline the role of B cells in the adaptive immune response
Multiply rapidly (clonal expansion)
Some form plasma cells that make antibodies
Others form memory cells that give immunity
Outline one mechanism for how differential gene expression in the early embryo is controlled.
Chemical gradients
Changes in gene expression based on concentration
Using light energy
Provides electrons that are used in light-dependent reactions
Describe three mechanisms to increase body temperature
Vasoconstriction at the skin
Shivering
Release of thyroxin
Uncoupled respiration
Hair standing up
Using examples, distinguish between density dependent and density independent factors of population control
Density dependent increase with population size
Eg. Disease, competition for resources
Density independent are unrelated to population size
Eg. Natural disasters, forest fire
Vesicles line up along the equation (cell plate)
Contain components of cell wall
Vesicles fuse and cell wall is formed on either side
Using examples, distinguish between continuous and discrete inheritance
Continuous is polygenic
Phenotypes occur along a spectrum
Usually genetic and environmental influences
Discrete is monogenic
Phenotypes are categorical
Describe how information is relayed in a reflex arc
Stimulus activates receptor
Sends signal down sensory neuron in PNS
Synapses with sensory neuron in spinal cord
Synapses directly with motor neuron in spinal cord OR via relay neuron
Sends signal down motor neuron in PNS
Activates effector (muscle/ gland)