structure and function in living organisms Flashcards
levels of organisation
organelles
cell: basic unit of life
tissue: Tissues are groups of cells that have a similar structure and act together to perform a specific function.
organ: a group of tissues in a living organism that have been adapted to perform a specific function
organ system: groups of organs that work together to perform a specific function
nucleus
contains genetic material in chromosomes whcih controls how cells grow and work
cytoplasm
supports cell structure
site of many chemical reactions
contains water and many solutes
cell membrane
holds the cell together
controls substances entering and leaving the cell
cell wall
gives cell extra support and defines its shape
chloroplasts
site of photosynthesis
chlorophyll pigments absorb light which is necessary for the plant to grow
vacuole
contains cell sap
used for storage for certain materials
also helps support the shape of cell
mitochondria
site of aerobic respiration
ribosomes
site of protein synthesis
organelles in animal cells
The nucleus
Cell membranes
Mitochondria
Ribosomes
Cytoplasm
organelles in plant
same than animal plus
cell wall made out of cellulose
chloroplasts for photosynthesis
permanent vacuole
elements in carbohydrates and lipids
carbon, hydrogen and oxygen
elements in protein
carbon, hydrogen, oxygen and nitrogen sometimes sulphur
monosacharide
a simple sugar eg sugar or fructose
disacharide
made out of two monosacharides
ex maltose formed by two glucose
or sucrose made of one glucose and one sucrose
polysacharides
formed when lots of monosaccharides join together
ex starch, glycogen and cellulose
what are proteins made of
amino acids
what are lipids made of
fatty acids and glycerol
test for starch
iodine turns form orange to black
test for protein
biuret turns blue to purple
test for sugars ex glucose
benedicts, sample to test tube add solutionwater bath for 5 mins
test for lipids
ethano, emulsion, sample into test tube add water and shake, will turn cloudy
enzymes
proteins that act as a biological catalyst
mechanism of enzyme action
Step One: Enzymes and substrates randomly move about in solution
Step Two: When an enzyme and its complementary substrate randomly collide an enzyme-substrate complex forms, and the reaction occurs
Step Three: A product (or products) forms from the substrate(s) which are then released from the active site. The enzyme is unchanged and will go on to catalyse further reactions
how does temperature affect enzyme activity?
if enzyme work at their ptimum temperature they will work faster.
on the other hand if temperture is above optimum the enzyme will denature
what is an enzymes optimum ph
normally 7
ones in stomach as produced in acidic condition is ph2
ones formed in alkali conditions such as the duodenum 8 or 9
what happens if the ph is too far from the optimum
it will denature
diffusion
Diffusion is the movement of molecules from a region of its higher concentration to a region of its lower concentration
active transport
The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration
osmosis
the movement of water from a area of high concentration to an area of low concentration of water through a semi permeable membrane.
how does surface area to volume ratio affect the rate of diffusion?
The larger the surface area to volume ratio, the quicker the rate of diffusion takes place.
photosynthesis formula
water + carbon dioxide = glucose + oxygen
limiting factors of photosynthesis
do not have unlimited supplies of their raw materials so their rate of photosynthesis is limited by whatever factor is the lowest at that time
ex light, carbon dioxide concentration and light intensity
how is a leaf adapted for photosynthesis
it has a large surface area to absorb more light and the diffusion of carbon dioxide
is also thin to make diffusion faster
key nutrients in a balanced diet
carbohydrates
vitamins
minerals (mineral ions)
dietary fibres
proteins
lipids
water
consequences of malnutrition
constipation-due to lack of fibre
starvation
coronary heart disease- diet to high in saturated fats and cholesterol
obesity
sources and functions of dietary elements
carbohydrates- source of energy, found in pasta, cereal, rice and potatoes
protein- growth and repair , found in meat, eggs, fish and nuts
lipids- insulation and energy storage, found in butter, oil and nuts
dietary fibre- peristalisis, found in vegetables and whole grains
vitamins- needed in small quantities to mantain health, found in fruits and vegetables
minerals- needed in small quantities to mantain health, found in fruits, vegetables, meat and vegetables
enzymes in mouth
amylase
enzymes in stomach
protease
enzymes in pancreas
all three types of enzymes
peristalisis
Peristalisis is a mechanism that helps moves food along the alimentary canal
what type of muscles control peristalisis
Peristalsis is controlled by circular and longitudinal muscles
Circular muscles contract to reduce the diameter of the lumen of the oesophagus or small intestine
Longitudinal muscles contract to reduce the length of that section the oesophagus or the small intestine
what is the purpose of digestion
to break down large, insoluble molecules into smaller, soluble molecules that can be absorbed into the bloodstream
amylase function
breaks down starch into maltose
maltase function
breaks down maltose into glucose
protease function
breaks down protein into amino acids