TERM 1 - 24' BIOLOGY EXAM

what were some conditions on early earth?

what were some conditions on early earth?

very little oxygen, significantly warmer, intense uv radiation, volcanic activity and constant bombardment by asteroids

what are cells the smallest unit of?

self-sustaining life

what is the spontaneous origin of cells theory?

new cells come from existing cells

what are the hypothesised processes needed for the spontaneous origin on cells on earth?

SAFP

S in SAPF

synthesis of simple organic molecules from inorganic compounds

A in SAPF

assembly of organic molecules to polymers

F in SAPF

formation of a polymer that can self-replicate

P in SAPF

packaging of molecules into membranes

what is the evidence for the origin of carbon compounds?

the miller-urey experiment

what is the miller-urey experiment

they replicated early earth conditions, a gas mixture (methane and ammonia) and energy, water vapour was then mixed producing animo acids

phospholipids spontaneously form vesicles due to

hydrophilic and hydrophobic properties

spontaneous formation of vesicles helped

the first cell form a compartmentalised region, semi-permeable

RNA is the presumed first genetic material because

it is self-replicating, can be a catalyst, mutates at higher rate, some viruses only have RNA

evidence for L.U.C.A

universal genetic code, ribosome structure, enzymes that synthesise DNA and RNA

approaches used to estimate dates of first living cells and L.U.C.A

chemical evidence, fossilised biological molecules and genetic evidence

chemical evidence

microscopic life trapped in rocks

fossilised biological molecules

fossilised stromatolites

genetic evidence

number of differences in genomes of two species

evidence for the evolution of the L.U.C.A

L.U.C.A in hydrothermal vents

explain the L.U.C.A in hydrothermal vents

the vents contain minerals that could have led to spontaneous generation of carbon-based polymers

polar covalent bond

unequal sharing of electrons

cohesion

water molecules stick together due to hydrogen bonding

adhesion

water sticking to a solid surface in the form of capillary action

water as a solvent

can only dissolve hydrophilic things such as polar molecules or ions

physical properties of water

buoyancy, viscosity and thermal conductivity

example of water being a good thermal conductor

water is good at maintaining body temperature

where did water come from?

hypothesised it arrived via asteroids

why has water remained on earth

sun is not close enough for water to boil and earth has a strong gravity

relationship between search for extra-terrestrial life and presence of water

earth is in the goldilocks zone

what does the goldilocks zone depend on

size/energy of star and size of planet (gravity)

osmosis

passive movement of water from low concentration to high concentration

passive

no energy required

isotonic

same concentration

hypotonic

lower concentration

hypertonic

higher concentration

aquaporin

channel protein that allows water to pass through more easily

plant cells have a

cell wall that prevents excess water

animals have

no cell wall

what do other eukaryotes do when they have no cell wall

they have adaptations

turgid

plants are in hypotonic medium

flaccid

when pressure inside drops to atmospheric levels

plasmolysis

in hypertonic solution, membrane shrinks away from cell

lysed

cell bursts in hypotonic solution

shriveled

shrinks in hypertonic solution

normal

when in isotonic solution

the higher the hydrostatic preassure

the higher the water potential

the higher the solute concentration

the lower the water potential

water potential

pressure potential + solute potential

the lipid bilayer

two layers of lipids, controls what enters and leaves the cell

larger molecules are

not as permeable

membrane is not permeable

to polar/charged particles

diffusion

passive movement from high concentration to low concentration

JETRAT

junction, enzymes, transport, recognition, attachment, transduction of hormonal signals

integral proteins

transmembrane proteins, full length of bilayer

peripheral proteins

only attached to the surface

facilitated diffusion

movement of particles from area of low concentration to high concentration through a channel protein

active transport

movement of particles from low concentration to high concentration, requires energy

glycoprotein

protein + carbohydrate, chain extending outside, important for recognition and joining of cells

glycolipids

liquids + carbohydrates, sticking outside, important to eukaryotes and recognition in immune system

fluidity

how easily something can move around

saturated fatty acids

less fluid than unsaturated fatty acids

cholesterol helps regulate fluidity

in animal cells

endocytosis

process of bringing material into the cell by engulfing it

endocytosis process

IPF

IPF definition

indentations, pinches off, forms a vesicle

vesicles are used in the cell to transport

SWFM

SWFM definition

protein synthesis by ribosomes, wrapped in a vesicle, fuses with golgi membrane, golgi modifies it and repackages

exocytosis

process of moving material out of the cell

exocytosis process

OIF

OIF definiton

materials out of the cell, inside a vesicle, fuses with membrane

cell growth process

GPFB

GPFB

membrane growth, vesicles pinch off, fuse with membrane, results in bigger membrane

voltage gated ion channels

channel proteins for ions that open or close based on changes in voltage

acetylcholine

channel and receptor for ions sodium-potassium pumps as an example of exchange transporters

during nerve transmission

a higher concentration of ions has to be present

ions must be pumped to

establish areas of high concentration

sodium-potassium pump is

an exchange transporter (sodium ions out, potassium ions in)

sodium-dependent glucose co-transporter

transports sodium ions and glucose together into a cell

cell adhesion molecules

surface proteins that assist in joining cells together

what bonds are responsible for the cohesive properties of water molecules

hydrogen bonds between water molecules

most enzyme molecules are

hydrophilic and soluble

water molecule diagram

oxygen = slightly negative, hydrogen= slightly positive

why are lipid tails hydrophobic

they and insoluble and non-polar and they provide a barrier between the cell, cytoplasm and external liquids

what is an animal example of buoyancy

black throated loon being able to float on water with feathers

what is an animal example of thermal conductivity

polar bears keeping warm in cold air with better insulation

what is an animal example of low viscosity

animals are more easily able to move in water

why did water retain on earth’s surface

gravity, temperature was just right for vapour to condense into liquid

why is the presence of water essential for life on earth

it is a good solvent and can support life

why are viruses considered non-living

they do not have a metabolism and are not able to reproduce

why are fatty acids or phospholipids important in the formation of cells and their components

allow compartmentalisation of cells and organelles

which substance must be transported in the blood by lipoprotein complexes

oxygen

what causes rates of diffusion to differ

different concentration gradients at the start

uptake of water by cells in the wall of the intestine and loss of water from a plant cell in a hypertonic environment are

processes that occur by osmosis

cell walls are

structures only found in prokaryotic cells

water molecules are highly cohesive which is

important for transport in xylem

where do hydrogen bonds form

between the slight positive charge of hydrogen and slight negative charge of oxygen in different water molecules