biology topics 1 + 2 Flashcards
function of nucleus
contains genetic information that controls the function of the cell
function of cell membrane
controls what enters and leaves the cell
function of cytoplasm
where many cell activities and chemical reactions within the cell occur
function of mitochondria
provides energy from aerobic respiration
function of ribosome
synthesises (makes) proteins
function of chloroplast
where photosynthesis occurs
function of permanent vacuole
used to store water and other chemicals as cell sap
function of cell wall
strengthens and supports the cell (made of cellulose)
function of dna loop
a loop of dna not enclosed within the nucleus
function of plasmid
a small circle of dna, may contain genes associated with antibiotic resistance
how is a sperm cell specialised
- head contains enzymes to break into egg
- tail to swim
- many mitochondria provide energy to swim
how is a nerve cell specialised
long to transmit electrical impulses over a distance
how is a muscle cell specialised
contains protein fibres that can contract when energy is available, making the cells shorter
how is a root hair cell specialised
- long extension to increase surface area for water and mineral uptake
- thin cell wall also allows this
how is a xylem cell specialised
- waterproofed cell wall
- cells are hollow to allow water to move through
how is a phloem cell specialised
- some cells have lots of mitochondria for active transport
- some cells have little cytoplasm for sugars to move through easily
what is the function of a xylem cell
to transport water from the roots to the rest of the plant
what is the function of a phloem cell
to transport sugars made from photosynthesis to different parts of the plant in translocation
definition of magnification
the degree by which an object is enlarged
definition of resolution
ability of a microscope to distinguish detail
definition of light microscope
basic microscope with a maximum magnification of 1500x, low resolution
definition of electron microscope
microscope with a much higher magnification (500,000x) and higher resolving power than a light microscope. this means that it can be used to study cells in much finer detail
how to calculate magnification
image size / actual size
cm in standard form
10^-2m
mm in standard form
10^-3m
micrometre in standard form
10^-6m
nanometre in standard form
10^-9m
what needs to happen before a cell can divide
- needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria.
- DNA replicates to form two copies of each chromosome
what happens in mitosis
- cell growth
- chromosomes condense (thicken)
- nucleus has been disassembled, chromosomes line up in middle of the cell
- one set of chromosomes is pulled to each end and the nucleus divides
- cytoplasm and cell membrane divide to form two identical celsl
where are plant stem cells found
meristem
properties of embryonic stem cell
can divide into most types of cell
uses of embryonic stem cell
therapeutic cloning: embryonic stem cells produced with same genes as patient, no rejection
properties of adult stem cell
can divide into a limited number of cells e.g. bone marrow stem cells can form various blood cells
properties of meristem
found in plants, can differentiate into any type of plant cell
uses of meristem
- clone rare species to prevent extinction
- crops with special features can be cloned
pros of using embryonic stem cells
- treats various diseases
- better to use cells from abortion clinics than waste
cons of using embryonic stem cells
- ethical and religious obligations with potential harm or death to the embryo
- embryo cannot consent
- can transfer viruses
pros of using adult stem cells
- adult gives consent
- does not kill donor
cons of using adult stem cells
- people may not want to be donors as it’s painful
- few cell types can be formed so fewer diseases can be treated
definition of diffusion
spreading out of particles from an area of high concentration to an area of low concentration
uses of diffusion
- oxygen and carbon dioxide in gas exchange (leaves and alveoli)
- urea from cells into blood plasma for kidney excretion
definition of osmosis
the diffusion of water from high to low concentration across a partially permeable membrane
uses of osmosis
movement of water into and out of cells
definition of active transport
the movement of substances from a more dilute solution to a more concentrated solution. This goes against the concentration gradient, requires energy from respiration
uses of active transport
- absorption of mineral ions from soil into plant roots
- absorption of sugar molecules from the gut to the blood
how does difference in concentration affect diffusion
the greater the difference in concentration, the faster the rate of diffusion
how does temperature affect diffusion
particles move more quickly at higher temperatures, so rate of diffusion increases
how does surface area of membrane affect diffusion
the greater the surface area, the quicker the rate of diffusion
adaptations of exchange surfaces
- large surface area
- thin membrane for short diffusion path
- ventilation (in animals to maintain concentration gradient)
- efficient blood supply (in animals to maintain concentration gradient)
definition of cells
basic building blocks of all living organisms
definition of tissue
a group of cells with a similar structure and function
definition of organs
different tissues performing specific functions
definition of organ systems
work together to form organisms
function of mouth
- teeth break up food
- tongue forms a bolus
- saliva contains amylase
function of oesophagus
muscular tube pushes food down to stomach, this is called peristalsis
function of stomach
muscular bag, contains acid to kill bacteria and make a low pH for pepsin
function of pancreas
makes enzymes and releases them into the small intestine
function of large intestine
- water diffuses into the blood
- waste material and undigested food form feces
function of anus
feces are excreted from the body
function of liver
makes bile, which is used to break down fats
function of gall bladder
stores bile
adaptations of small intestine
- thin walls (one cell thick)
- large surface area (more space for absorption of nutrients
- network of capillaries (large blood supply maintains the concentration gradient)
how does bile increase rate of breakdown with lipase
- neutralise the acid from stomach (bile is an alkali)
- emulsifying fat to form small droplets to increase surface area
what does iodine test for and what colour change
starch
brown to black
what does buiret test for and what colour change
protein
blue to purple
what does benedict’s test for and what colour change
glucose
blue to orange/brick red
what does Sudan III test for and what colour change
lipids
red layers form
what are enzymes
proteins and biological catalysts
what do enzymes do
build up or break down substances
what do enzymes and substrates form
an enzyme-substrate complex
what happens after an enzyme-substrate complex is formed
products are released and the enzyme can be used again
what shape is the active site compared to the substrate
the active site has a specific shape while the substrate has an opposite, complementary shape
what do digestive enzymes do
convert food into small soluble molecules that can be absorbed into the bloodstream
what are the products of digestion used for
to build new carbohydrates, lipids and proteins. some glucose is used in respiration
what is the substrate and product for carbohydrase
carbohydrates
simple sugars
what is the substrate and product for protease
proteins
amino acids
what is the substrate and product for lipase
lipids
fatty acids and glycerol
what happens when you increase the temperature for an enzyme
the rate of reaction increases until it reaches the optimum temperature (where the rate of reaction is highest) then it starts to decrease
why do higher temperatures decrease rate of reaction for enzymes
the shape of the active site is changed so the substrate will not fit perfectly so the enzyme has become denatured
what happens when you change the pH for an enzyme
the rate of reaction increases whether it’s more acidic or more alkaline
why does rate of reaction change with pH for an enzyme
it changes the shape of the active site so the substrate will not fit perfectly so the enzyme has become denatured
what stops the trachea from collapsing
rings of cartilage
order of blood in heart
vena cava > right attriium > right ventricle > pulmonary artery > lungs > pulmonary vein > left attrium > left ventricle > aorta > rest of body
properties of earty
- away from heart
- high pressure to reach all parts of body
- thick strong walls to give high pressure
- narrow lumen
properties of capillary
- substances dissolve in and out
- very thin walls (short diffusion pathway)
- very small lumen
properties of vein
- into the heart
- blood under low pressure
- thin walls
- wide lumen
- valves to prevent backflow
why is the left ventricle thicker
needs to pump to the whole body and be more powerful
why do valves prevent backflow
so oxygenated and deoxygenated blood don’t mix
properties of red blood cell (carries oxygen)
- contains haemoglobin
- forms oxyhaemoglobin
- biconcave shape for large surface area
- no nucleus for more space for haemoglobin
properties of white blood cell (defends against pathogens)
- some produce antibodies
- other WBC to engulf pathogens
- some produce anti-toxins to neutralise toxins from pathogens
properties of platelets (form clots)
- fragments of cell (no nucleus)
- form blood clots to prevent blood loss and infection from pathogens
properties of plasma (carry substances)
- straw like liquid
- main component
- transport dissolved substances
what is coronary heart disease
layers of fatty material build up inside the arteries, narrowing them and reducing oxygen for the heart
