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semester 2 bio exam revision - Coggle Diagram
semester 2 bio exam revision
Plants
basic plant structures
root system
osmosis- plants absorb water from the soil via osmosis through the root hair cells. these adapt for this by increasing the sa:v ratio and therefore speeding up osmosis
the absorbed water is then transported from the roots to the rest of the plant for purposes such as being a reactant in photosynthesis, supporting the leaves and shoot's rigidity. cooling the leaves via evaporation and transporting dissolved minerals
lateral root- offshoot roots of of the primary root
shoot system
xylem
xylem- transports water from the roots to the shoots and out the plant
one way flow through a hollow cylindrical structure- no end walls between cells
phloem
conducts sucrose and other nutrients to the rest of the plant. phloem contains sap to transport materials around the plant as needed
two way flow- end walls of the cell have perforated holes
leaves expose the surface to more sunlight, provide a site for gas exchange and conserve water
stomata
stomata are openings in the leaf that let CO2 in to adapt for photosynthesis, O2 is released through them
epidermis
palisade layer
palisade cells packed full of chloroplast
cuticle
waxy surface reduces water loss from the surface
guard cell
regulate the opening of the stomata
chloroplasts
converts light energy into chemical energy for use in the plant
bundle sheath cell
xylem & phloem
spongey layer
spongey cells with air pockets in between allow for gas movement
flower structure
modified leaves specialized for reproduction
gametes- male contained in pollen in the anthers and female contained in the ovule
plant tissues
vascular tissue for transport and support
ground tissue for synthesis of sugars, storage and support
dermal tissue for protection
monocots
seeds with one cotyledon eg corn, wheat, grass
flowers generally divided in 3 parts
leave generally have parallel leaf veins
dicots
seeds with two cotyledons eg magnolias, roses
flowers usually in 4-5 parts
leave usually have a distinct vein network
photosynthesis
equation= carbon dioxide + water > (sunlight & chlorophyll) glucose + oxygen
6CO2+ 6H2O > C6H12O6 + 6O2
uses for glucose- cellulose for cell growth, proteins for growth and enzymes, creation of starch for storage and fats and oils for storage
the conversion of usable sunlight energy into chemical energy
phases of plant growth
growth
germination- seed coat ruptures and the radicle extends into the ground to begin collecting nutrients
cotyledon emerges and produces the first leaves on the emerging shoot
pollination- the process which brings together the male and female gametes- with male gametes found on the anthers and the female gametes found in the ovules
wind pollinated flowers- generally have no petals, with lots of flowers packed onto one 'spike'. large stigmas with exposed anthers and no scent or nectar
fruiting- fruit develops from flowers as a method of seed dispersal, with the ovary wall hardening to form a fruit. the seed of the fruit contains a new plant (embryo) as well as storing food and
factors affecting germination: oxygen, water, temperature, pH
fertilization/pollination
relationship between pollinators and their plants
genetic diversity
seed dispersal- plants need various methods of seed dispersal to reduce competition for resources in one area
wind
water
fruit
animals
respiration
equation- C6H12O6 + 6O2 > 6CO2 + 6H2O
transpiration- the loss of water vapor from the stems and leaves of plants
light energy converts water in leaves into vapor which exits the leaf through the stomata
new water is absorbed by the roots from the soil- creates varied pressure between the roots (high) and the leaves (low)
water flows via the xylem along the pressure gradient to replace lost vapour from the leaves
Introduction to biology and skills
microscopes- light, TEM, SEM
Light microscopes
image quality
colour, can use dead or alive specimens, lower resolution and limited magnification
parts
field of view
the diameter of the viewing area that can be seen under a microscope- find fov in mm, convert to micrometres and divide by estimated object size
magnification calculations
TEM- uses beam of electrons through an object and takes a reading of the electrons. very clear resolution, can magnify up to 500 000 x. images will always be in black and white and 2d, can only use non living specimens
SEM- uses a beam of electrons which bounce back and produce a 3d image with texture and shape. high resolution, not as much as TEM. black and white image. non living specimens
Cell biology
organelles structure and function
nucleus
nucleolus
golgi body
chloroplast
rough/smooth er
mitochondria
ribosomes
cytoskeleton
vacuole
cell wall
mitosis
eukaryotic cell replication
plant cells
plant cells do not change shape before undergoing mitosis, and do not contain centrioles to assist the mitotic spindle, which does not contain asters either.
cytokinesis in animal cells occurs by the formation of a cell plate down the middle of the cell, which consists of plasma membrane and other cell wall parts, separating two daughter cells
animal cells
animal cells become more rounded before mitosis
cytokinesis occurs in animal cells as contractile cytokinesis, a ring-like filament structure called the contractile ring pinches the cell in two, producing an indentation called the cleavage furrow to produce two new daughter cells
prophase
chromosomes start to condense, mitotic spindle begins to form
mitotic spindle- a structure composed of microtubules that forms between centrosomes as they move apart to opposite ends of the cell. microtubules can bind to the centromere on chromosomes on the kinetochore- a patch of protein on each side of the centromere. microtubules that don't bind to kinetochores grab onto microtubules from the opposite side to stabilise. more microtubules extends towards the edge of the cell, forming the aster
prometaphase
mitotic spindle captures chromosomes and starts to organise them, nuclear envelope breaks down and releases chromosomes
metaphase
chromosomes are all captured and aligned at the metaphase plate. the spindle checkpoint occurs, checking all kinetochores are attached to microtubules from opposite poles of the cell
anaphase
sister chromatids are separated and pulled to opposite poles of the cell, the microtubules not attached to chromosomes elongate, making the cell longer
telophase
cell starts to re-establish structures, mitotic spindle breaks down, nucleus and nuclear membrane starts to reform for the two new daughter cells, chromosomes start to de-condense cytokinesis begins
MRSGREN- the characteristics that define life.
Movement- all living organisms must be able to move itself/parts of itself as an essential process for capturing food/avoiding predators
respiration- the ability to convert energy from nutrients such as carbs and fats into usable energy for cell processes
sensitivity- ability of living organisms to respond to outside stimulus from their environment
Growth- the ability to increase mass, using extra energy from respiration to contribute to making new cells and therefore growth
reproduction- the ability to asexually or sexually created offspring from an existing organism. important in the survival of the species
excretion- removal of waste products from the organism
nutrition- the requirement for nutrition or food for survival, reproduction and growth processes
SA: V ratio
SA: Ratio refers to the ratio existing between the surface area and volume of a structure. a larger surface area allows quicker diffusion across a structure, which is essential in many processes such as active & passive transport
Microbiology
Prokaryotes structure
optimal conditions for bacterial reproduction
gene transfer
conjugation
antibiotic resistance
transformation
transduction
non pathogenic vs pathogenic
bacterial shapes
antimicrobial vs antibiotics
aseptic technique
methods of transmission
airborne: certain pathogens may be transferred via air from the host through actions such as coughing or sneezing
vectors: pathogens may be transmitted through intermediary organisms that don't develop symptoms themselves but are still capable of transferring the virus e.g. insects
contamination: ingestion of pathogens growing in or on edible food sources
direct contact: transfer of pathogens via physical contact or exchange of bodily fluids
binary fission
asexual prokaryotic reproduction
replication of DNA
cell elongates, separating the DNA
cross wall starts to form, membrane invaginates, forming a septum
cross wall forms completely
daughter cells are genetically identical
DNA
discovery of DNA- scientists
Watson & Crick
genes- genes are long portions of chromosomal DNA generally 10, 000-50, 000 base pairs long that code for specific traits or proteins/groups of proteins
chromosomes- entire chains of DNA with a group of stabilizing proteins, wrapped around a protein called histones to form a bundle. chromosomes generally exist in an unravelled state inside the nucleus and only condense to make transfer during cell replication easier
replication
1) the enzyme DNA helicase pries apart the two strands from each other like a zipper- a leading strand (5'-3') and a lagging strand (3'-5')
2)
RNA/DNA primase then goes along both strands and creates a starting point for DNA polymerase to go along the strand and attach matching nucleotides to each strand. RNA primase is only needed once on the leading strand as DNA polymerase and the leading strand run in the same direction, meaning it can smoothly go along the strand in one go. However, RNA primase must create several starting points on the lagging strand as it goes in the opposite direction to DNA polymerase, meaning the lagging strand must be synthesized in short burst, creating segments called okazaki fragments
3) another polymerase goes along the strands and replaces all the RNA primase
4) an enzyme called DNA ligase goes along and joins all the okazaki fragments together
structure- double helix
complementary base pairs
adenine & thymine, cytosine & guanine
joined by hyrdogen bonds- A& T form two bonds, C & G form 3
repeating polymer- nucleotides
three components of a nucleotide- phosphate group, pentose sugar, nitrogenous base
stable arrangement- the arrangement of the two strands running in opposite directions to each other (5'-3' and 3'-5')
