Biology Flashcards
what is the cytoplasm ?
liquid gel which contains enzymes, where chemical reactions happen
what are mitochondria ?
structures where oxygen is used and energy is released during aerobic respiration
what is the function of the permanent vacuole ?
- stores cell sap
- provides rigidity and cell support
what is cell sap ?
weak solution of: salt, sugar, mineral ions, waste molecules
how are erythrocytes specialised ?
- haemoglobin
- biconcave shape
- anuclear (no nucleus)
- mature cells have no mitochondria
give advantages of biconcave shape of erythrocytes
- large SA
- can squeeze through capillaries
how are sperm cells specialised ?
- flagellum allows movement
- head is streamlined
- head is acrosome (contains digestive enzymes)
- middle packed with mitochondria
what do egg cells carry ?
female DNA and store food to provide energy / building molecules for early stages of developing embryo
what happens to cell membrane of egg once fused with sperm ?
strengthens to prevent other sperm from entering
give the total number of human chromosomes
46
how is genetic material contained in bacterial cells ?
free in cytoplasm (in rings - plasmid)
what is the term for bacteria division ?
binary fission
what do bacteria often produce that is harmful ?
toxins
give 3 ways in which white blood cells help defend the body
- ingest microorganisms
- produce antigens
- produce antitoxins
what are antitoxins ?
antibodies that neutralise toxins
how is antibiotic resistance avoided ?
- patients finish course of antibiotics
- medics avoid unnecessarily prescribing
what is the most common example of a ‘super bug’ ?
MRSA
what type of pathogen are antibiotics used for ?
bacteria
give 4 functions of proteins
- structural components (muscles/tendons)
- hormones
- antibodies
- enzymes
enzymes at high temp are described as …
denatured
enzymes at low temp are described as …
inactive
what is the optimum temp for most human enzymes ?
37 degrees Celsius
what is pepsin and what is its optimum pH?
stomach enzyme at a pH of 2 (acidic)
what does changing the pH do to enzymes ?
alters intermolecular forces and bonds that holds the enzyme, altering active site shape
where is bile produced ?
the liver
what is the function of bile ?
neutralises stomach acid and emulsifies fat
how is food broken down in the stomach ?
- mechanical digestion from muscular walls
- HCl produced gives opt. pH for pepsin to work and kills pathogens
function of pancreas (for digestive system)
releases enzymes into small intestine
function of large intestine
absorbs water and ions
function of small intestine
absorbs soluble food molecules
where is bile stored and then released ?
gall bladder into small intestine
what is peristalsis ?
contraction of gut muscles to move food along
where is amylase produced ?
salivary glands / pancreas / small intestine
where are proteases produced ?
stomach / pancreas / small intestine
where is lipase produced ?
pancreas / small intestine
Describe inspiration (6 steps)
- intercostal muscles contract
- ribs move up and out
- diaphragm contracts and flattens
- thorax vol increases
- air pressure drops
- air drawn in
Describe expiration (6 steps)
- intercostal muscles relax
- ribs move down and in
- diaphragm relaxes and curves
- thorax vol decreases
- air pressure increases
- air pushed out
give the path of structures air passes from the mouth
pharynx - trachea - bronchus - bronchioles - alveoli
how is anaerobic respiration not very efficient?
- glucose only partially broken down
- lactic acid is a byproduct
give the anaerobic respiration equation
Glucose — Lactic Acid + energy
give the function of phagocytes
engulf and digest microorganisms
give the function of T-lymphocytes
destroy cells infected with viruses and produce memory cells
give the function of B-lymphocytes
produce antibodies, antitoxins and memory cells
what is coagulation ?
blood clotting
what is a blood clot made up from ?
a mesh of fibrin fibres
describe what happens after tissue is damaged
- chemicals released cause platelets to stick together
- platelets release calcium ions and others which trigger clotting reaction
what is genetic condition in which blood cannot properly clot ?
haemophilia
what causes blood groups ?
antigens on erythrocytes surface
describe the process of a heart beat
- SAN produces electrical current (atria contract)
- current passes through AVN, causing ventricles to contract
what does ECG stand for ?
electrocardiogram
state the function of the kidneys
remove urea from blood
adjust water and ion content of the blood
what are the filtration units in the kidneys called ?
nephrons
what is urea ?
waste product produced in liver when amino acids converted to fats and carbs
describe ultra filtration
- blood arrives at renal artery and enters capillaries in Bowman’s capsule
- high pressure forces small molecules out of the blood
which small molecules are involved with ultra filtration ?
urea / water / glucose / amino acids / mineral ions
describe reabsorption
- glucose, mineral ions and water are moved back into blood by active transport
how much glucose is reabsorbed ? (nephron)
all glucose is reabsorbed in the nephron
how much water / mineral ions are absorbed ? (nephron)
sufficient amounts of each are reabsorbed to maintain balance
which molecules are released as waster (kidneys) ?
urea / excess ions / water
after reabsorption, describe the path to the bladder …
- collecting duct - ureter - bladder
what do receptors do ?
detect change in environment (stimulus)
what is the axon ?
long structure made from cytoplasm and cell membrane which transmits impulses
what is the axon usually covered by ?
fatty sheath (acts as electrical insulator)
what is dendrite ?
structure at end of axon which communicates with other neurons (forms synapses)
what is the function of sensory neuron?
receives signals from receptor and carries them as electrical impulses to CNS
what is the function of relay neuron?
connects sensory and motor neurons within CNS
what is the function of motor neuron?
sends messages from CNS to effector
give the length + no. of dendrites for sensory neuron
one long
give the length + no. of dendrites for relay neuron
many short
give the length + no. of dendrites for motor neuron
many short
give the length + no. of axons for sensory neuron
one short
give the length + no. of axons for relay neuron
many short
give the length + no. of axons for motor neuron
one long
describe how impulses pas between neurons
- neurotransmitter (chemical) released
- neurotrans. diffuses across gap and attaches to specific receptors
- new nerve impulse initiated
what is a reflex ?
quick, automatic response to a stimuli
state reflex arc
stimulus - receptor - sensory neuron - CNS - motor neuron - effector - response
define homeostasis
the maintenance of a stable, relatively constant internal environment
what part of the brain controls body temp?
hypothalamus
how does standing up hairs keep body warm ?
traps insulating layer of air
how much nitrogen in the atm ?
78%
what is nitrogen fixation ?
converting atm nitrogen to nitrates
how does nitrogen fixation occur ?
- lightning
- nitrogen fixing bacteria
where do nitrogen fixing bacteria live ?
root nodules of leguminous plants
state the 4 main steps of nitrogen cycle
- nitrogen fixation
- decomposition
- nitrification
- denitrification
what is decomposition ?
fungi/bacteria break down organic material and convert nitrogen compounds (proteins) into ammonium compounds
what is nitrification ?
nitrifying bacteria changing ammonia (in ammonium compounds) into nitrites, then nitrates
what is denitrification
denitrifying bacteria changing nitrates into ammonia and atm nitrogen
state the 6 main stages of the Carbon cycle
- photosynthesis
- respiration
- feeding
- combustion
- decomposition
- breakdown of waste / dead matter
what makes up a DNA nucleotide ?
nitrogenous base
deoxyribose sugar
phosphate group
what is a gene ?
length of DNA on a chromosome which determines a specific characteristic
define heterozygous
inheriting both recessive and dominant alleles of a gene
define homozygous
inheriting either two dominant/recessive alleles of a gene
what two sex chromosome do males have ?
XY
what two sex chromosomes do females have ?
XX
describe how a male if first developed
Y chromosome activates production of a protein, which activates testis-forming pathway
Testes produce hormones, leading to other organ formation
describe how a female if first developed
Protein is not produced, so ovary-forming pathway is activated. Ovaries produce hormone…
what is polydactyly ?
genetic disorder where baby is born with extra fingers/toes
what are the symptoms of Huntington’s disease ?
dementia and chorea
symptoms don’t appear until late
what is genetic screening ?
analysis of a person’s DNA to see the alleles
what is the term to describe stem cells ?
undifferentiated
describe the process of genetic engineering
- cut out gene using restriction enzymes
- cut open plasmid using same restrict. enz.
- gene inserted in plasmid (now a vector)
- join DNA strands with DNA ligase
- insert vector into organism
what is gene therapy ?
replacing ‘genetic disease genes’ with healthy genes
