Structures / Functions of Living Organisms Flashcards
Mrs Gren H
Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrient, Homoeostasis
what is Homoeostasis?
control of internal conditions (like temperature or water content)
function of nucleus
controls cell and stores genetic material
Cell membrane does?
controls what enters / leaves the cell
what is the Cytoplasm? Function?
gel-like substance where chemical reactions happen
contains enzymes
what are Chloroplasts ?
site of photosynthesis
contain green chlorophyll
what is the Cell wall in plants?
supports and strengthens the cell
made of cellulose
what is the function of the Vacuole ?
contains sap (sugars and salts)
Describe Plants
multi cellular
have chloroplasts to photosynthesise
have cell walls made from cellulose
store carbs as sucrose or starch
Describe Animals
multi cellular
nervous coordination
store carbs as glycogen
Describe Fungi
some single celled others have body of mycelium made of hyphae (nuclei) cells walls made from chitin saprotrphic excretion stores carbs as glycogen
what is a pathogen ?
an organism that can cause a disease
examples of pathogens
protocist :plasmodium, causes malaria
bacteria :pneumococcus, causes pneumonia
virus :influenza virus, causes flu and HIV
what is a catalyst
substance which increases speed of reaction without being changed or used up in the reaction
what are enzymes
biological catalyst
used to speed up metabolic reactions in body
enzymes are all proteins
why is the shape of enzymes important?
has active site - part substrate joins enzyme
only speed one reaction as substrate must be correct shape to fit active site
this is called ‘lock and key’ model
what is a substrate?
molecule changed in a reaction
what is the right temperature for enzymes ?
optimum temperature (reaction goes fastest) for human enzymes is 37°C
what happens to enzymes when too hot?
at first increases rate of reaction as more heat = more energy = more collision
if too hot, bond holding enzymes break
this makes enzyme lose shape and can’t fit substrate so is denatured, this is irreversible
what happens to enzymes when too cold?
low temperatures means less energy = less collision so slower reaction until they get so cold they become inactive
what happens to enzymes when the pH isn’t right?
what is the optimum pH?
do all enzymes work best at this pH?
pH interferes with bonds holding enzymes, changes shape and can denature it
usually optimum pH is neutral 7
pepsin (breaks proteins in stomach) works best at pH 2 to be well suited for acid conditions
Define Diffusion
the net (overall) movement of particles from an area of high concentration to an area of low concentration
What does diffusion happen in?
Simplest type of diffusion…
happens in liquids and gases as their particles move
simplest type is when gases diffuse through each other (like perfume into air)
How / what substances move through cell membrane?
substances move through cell membrane by diffusion, osmosis and active transport
only small molecules can diffuse (like glucose)
bigger molecules can’t fit (like starch)
Define osmosis
net movement of water molecules from a high water concentration to a low water concentration across a partially permeable membrane
what is a partially permeable membrane ?
membrane with small holes in it
cell membrane are partially permeable
What direction do water molecules go during osmosis?
How is water controlled in/out of cell
water molecules move randomly, some go both ways
tissue fluids surround cell so if cell needs water/has too much, it can become more/less dilute
what is turgor pressure ?
when contents of cell push against cell wall (plants) which helps support and helps support plant
describe a turgid cell
plump swollen cell (healthy)
holds shape of cell with turgor pressure
describe a flaccid cell
cell without enough water and turgor pressure
inelastic cell wall keeps cells structure in position but cell becomes droopy
Define active transport
movement of particles against a concentration gradient (like low concentration to high concentration) using energy released during respiration
How is active transport used in the gut?
high concentration of nutrients from gut diffuse naturally into blood
sometimes lower concentration in gut, so active transport takes place to allow nutrients go in blood
this stops us from starving
what are the factors of diffusion/osmosis/active transport rates?
what means faster?
surface area to volume ratio - larger surface area to ratio means faster
temp - hotter it is = more energy = faster
concentration gradient - bigger concentration difference means faster (not active transport)
What changes rate of diffusion?
concentration difference (higher concentration difference = faster diffusion)
Describe protocists
Examples?
single celled microscopic
have nucleus
some have chloroplasts (chlorella)
some animal like (amoeba)
Describe bacteria
Examples?
single celled microscopic no nucleus plasmid contains DNA some photosynthesise Lactobacillus / Pneumococcus
Describe viruses
Examples ?
can only reproduce in living cells (depend so parasite)
protein coat around some genetic material
Influenza virus
what does urine contain?
urea, water and salts
