biology unit 1 Flashcards
1
Q
equation for total magnification
A
magnification of eyepiece lens multiples by magnification of objective lens
2
Q
why does the specimen or material on the slide have to be thin
A
so that light or electron beams can pass through it
3
Q
why is a cover slip needed
A
to protect the specimen and also the lens if they should touch
4
Q
microscope
why are stains important
A
to help distinguish different features in the specimen
5
Q
one limitation of electron microscope
A
they can only examine dead material.
6
Q
features and role of a plasma membrane
A
*protects cell from its surrondings
* made from a phospholipid bilayer
* regulates movment of substances in and out of the cell
7
Q
features and role of rough endoplasmic reticulum
A
*serious of single flattened sacs enclosed by a membrane
has ribosomes attached to it
*synthesizes and transports proteins
* the membrane of the retiuclum is a phospolipid bilayer
8
Q
features and role of the smooth endoplasmic retiuclum
A
- a serious of single tubular sacs made of membrane
- no ribosomes is attached to it
- synthesis lipids and detoxifies chemicals
9
Q
features and role of the mitochondria
A
- oval shaes and surronded by a double membrane
- the inner membrane folds into projections known as cristae
- the area around the folds is called the mitochondrial matrix
- contains 70s ribosomes and DNA
- site of aerobic respiration which means it produces adenosine triphosphate.
10
Q
mitochondria and atp production
why do muscle cells have lots of mitochondria
A
- this is because they are highly active and need lots of energy to keep the body moving
11
Q
features and role of cytoplasm
A
- fluid that fills a cell
- 70% of it is water
- many molecules are dissolve in the cytoplasm such as proteins, sugars, ions, enzyme and fatty acids and amino acids
- site of many metabolic processes
12
Q
features and role of ribosomes
A
- can be in the cytoplasm or attached to the endoplasmic reticulum
- ribosomes can be found in the cytoplasm, attached to the RER or in chloroplasts
- they are 80s in cytoplasm and RER and 70s in mitochondria and chloroplasts
- site of protein synthesis
13
Q
features and role of golgi apparatus
A
a series of single curved sacs enclosed by a membrane
* transport vesicles form at ER and fuse with GA and they empty proteins and lipids into the lumen of the GA.
* the GA modifies proteins and packages them in vesicles for transport
14
Q
features and function of lysosomes
A
- enclosed by a single membrane
- special type of golgi vesicles that contain lysozymes which are enzymes
- contains digestive enzyme
- destory old organelles and pathogens
15
Q
features and role of centrioles
A
- two hollow cylinders
- arranged at right angles to each other
- make the mitotic spindle in cell division
16
Q
features and role of nuclear envelope/ nucleus
A
- surronded by a double membrane which are both phospholipid bilayers
- pores in the nuclear envelope.
- the pores control the passage of ions, molecules and RNA between the nucleoplasm and cytoplasm
17
Q
first mention what can be found in the nucleus
features and role of the nucleolus/ nucleus
A
- inside the nucleus there is the chromatin and nucleolus.
- nucleus contain linear chromosomes made up of DNA
- the nucleolus is a region of the nucleus where there is dense DNA nd protein
- the nucleus controls the actions of the cell
- ribsomes are made in the nucleolus
18
Q
how are ribosomes made in the nucleolus
A
ribosomal RNA joins with associated proteins in the nucleolus to make ribosomal subunits
19
Q
features and role of vesicles
A
- small membrane bound sacs in the cytoplasm
- they store substances and transport proteins and lipids from the golgi apparatus to target cells
20
Q
example of tissues
A
- muscle tissue
- xylem tissue
21
Q
example of organs
A
- animal heart
- plant leaf
22
Q
example of organ systems
A
- the female reproductive system
- digestive system
- nervous system
23
Q
features of palisade mesophyll cells and function
A
- function is for photosynthesis
- cylindrical in shape, packed tightly close to the upper part of the leaf
- contains lots of chloroplast to maximise light absorption
- large vacuole which keeps the leaf structure rigid.
24
Q
features and function of root hair cells
A
- found in the epithelium where there is no thickening
- fine protrusion which provides a large surface area to volume ratio
- thin cell wall to maximise water absorption
- lots of mitochondria for energy for active transport of minerals from soil into cell
25
due to a large surface area to volume ratio, what do root hair cells absorb from the soil
* water
* dissolved minerals from the soil
26
are root hair cells prokaryotes or eukaryotes
they are eukaryotes and not uses for photosynthesis
27
why are root hair cells not used for photosynthesis
this is because they are found undergorund so they do not contain chloroplasts as there is no light for photosynthesis
28
structure of sperm cell
* undolipodium(tail) for movement to swim to egg.
* midpiece of the sperm contains mitochondria which provides energy for movement (from respiration)
* acrosome contains enzymes which digests the zona pellucida (outer layers of the egg)
* haploid nucleus which has one set of chromosomes
29
where is the genetic material for the sperm cell located
in the head of the sperm cell inside a nucleus
30
what is the advantage of sperm cells being very small
males can make many of them to increase the chance of fertilisation
31
structure of egg cell
* bigger than sperm cells
* cytoplasm contains lots of energy and rich material which is used when embryo starts to grow
* follicle cells (corona radiata) suppiles cell with vital proteins
* zona pellucida stops more than one sperm from fertilising the egg
* special vesicles ( cortical granules) which prevents polyspermy- where more than one sperm fertilises an egg
* haploid nucleus that has half of the chromosomes of a body cell
32
explain the importance of red blood cells being biconcave shaped
* optomises their surface area to volume ratio which allows more oxygen and carbon dioxide to diffuse into the haemoglobin.
* they are small and round so can squeeze through ***blood vessels.***
33
what is a key difference between red blood cells and white blood cells
* red blood cells do not have a nucleus which means they cannot divide
34
where are red blood cells made
* made in the bone marrow
35
features and function of white blood cells
* contain a large nucleus sometimes with protrusions
* can squeeze through*** capillary walls****
36
where can white blood cells be found and what is the importance of this
* can be found in tissues as well as blood which means that they can move to sites of infection easily
37
what is another word for a phagocyte
* neutrophil
38
where are white blood cells made
* made in the bone marrow and lymph nodes
39
what surfaces do epithelial cells line
any surfaces that is in contact with the external envrionment and some internal organs such as the lungs
40
what two types of epithelial tissue are in the lungs
sqamous and columnar epithelium
41
structure and function of sqaumous epithelium tissue
* egg shaped nuclei
* one cell thick
* good for surfaces where diffusion occurs for example the lungs
42
why are squamous epithelium tissue good for the lungs
because it provides a short diffusion pathway
43
what airways are mainly lined with ciliated columnar epithelium cells
trachea and bronchi
44
structure and function of ciliated columnar epithelium tissues
* contains lots of mitochondria
* contains ciliated cells which move mucus away from respiratory tract
* contain goblet cells that secrete mucus so pathogens are trapped
45
how does copd affect cilia
causes it to slow down and stop beating and eventually die off which causes mucus build up
46
what are blood vessels lined with
endothelial tissues
47
how do blood clots form
when there is a damage to tissue and if there is a damage to an artery and a clot forms this can cause a number of health related problems
48
what are blood vessels/ endothelial tissues made up of
a single layer of flat long cells which are orientated lengthways in the diretion of blood flow
49
function of blood vessels
to provide a smooth surface so that blood flows easily over them
50
what is atheroscleorosis
the disease process that leads to coronary disease and strokes- cardiovascular diseases.
51
two ways an atheroma can affect an artery
*it can either block an artery directly
*increase its chances of being blocked by a blood clot also known as thrombosis
52
explain what happens when blood thickens due to smoking
causes fatty deposits to build up on the walls of arteries and increases the risk of clotting.
53
what can skeletal muscle alos be known as
striped or striated muscle
54
what are muscle fibres
long specialised cells
55
structure of muscle fibres
* cylindrial in shape enclosed by a sarcolemma
* are multinucleate
* contain myofibrils with cross striations
* arranged in parallel to give striped appearance
56
what causes the pattern of skeletal muscles
the arrangement of protein filaments actin and myosin
57
what are the thin filaments made up
actin
58
what are the thick filaments made up
myosin
59
where can thick filaments be found
in the A band or dark band
60
why are the outer regions of the a band darker
this is because they contain overlapping myosin and actin filaments
61
why is the h zone not as dark
because it only contains myosin filaments
62
function of the m line
connects the myosin filaments in the a band
63
what does the l band or light band contain
only thin actin filaments
64
what is the function of the z line
connects these actin filaments and is the boundary of the sarcomere
65
what happens on muscle contraction (6marks)
* the h zone narrows
* the outer darker regions of the a band becomes wider
* the a band remains the same size
* the l band narrows
* the z lines move closer together
* the length of each sarcomere decreases
66
explain the transmission across a neuromuscular junction
* arrival of action potentials at synpatic knob causes depolarisation of presynaptic membrane
* this stimulates calcium channels to open in the pre synpatic membran and calcium ions begin to diffuse into the synpatic knob
* this causes synaptic vesicles to fuse with the membrane and open up
* this causes acetylcholine to be released and diffuse acorss the synaptic cleft
* they attach to specific protein receptor sites on the sarcolemma
* causes entry of sodium ions causing depolarisation
* an action potential occurs along the sarcolemma and into the muscle fibre which stimulates the release of calcium ions and begins a muscle contraction
acetylcholine is broken down by cholinesterase into acetyl and choline
* taken up by active transport into synaptic knob
67
what two things do muscle fibres have and why
mitochondria and nuclei because the mitochondria provides lot of ATP in order to power muscle contraction
68
function of myofibrils
site of muscle contraction
69
what is the muscle that contracts called
agonist
70
what is the site of muscle contraction
myofibrils
71
differences between high and fast twitch muscle fibres
* slow muscle fibres contain lots of mitochondria, lots of capillaries, do not tire easily and contains large oxygen and glucose stores for long periods of exercise
* fast twitch muscle fibres do not have alot of mitochondria, few capillaries, tire easily and have little oxygen and glucose stores
72
why do people with more fast twitch muscle fibres move quickly
this is because the muscles contract quickly and strongly in short bursts of time using energy from anaerobic respiration.
73
why are people who have more slow twitch muscle fibres better as marathons
this is because they use aerobic respiration and can work for a long time without getting tired
74
what are neurones
cells that transmit information from receptors to effectors.
75
what do sensory neurons do
connect sensory receptors to the central nervous system
76
function of motor neurons
communicates from cns to effectors
77
what are relay neurones
intermediate neurons
78
function of relay neurones
receive impulses from sensory neurone and relay them to motor neurones
79
what are the structures of neurones
* cell body
* nucleus
* dendrites
* schwann cell
* node of ranvier
* axon and axon terminals
* myelin sheath
80
role of cell body
contains the nucleus and materials needed for the cell are made here
81
role of dendrite
recieve chemical signals from the axon terminal of other neurons
82
role of schwann cell
produces the myelin sheath
83
role of node of ranvier
gaps in the myelin sheath which allow the electrical impulse to pick up the speed
84
role of myelin sheath
electrically insulating layer
85
role of axon
adapted to conduct an electric impulse called an action potential
86
what are non myelinated cells usually responsible for
transmitting pain such as aches and soreness rather than sharp pain and detect temperature change
87
describe the structure of myelinated sheaths
they contain myelin sheath, are white, transmit impulses very fast and have nodes of ranvier
88
structure of non myelinated sheaths
do not have myelin sheaths, are grey, transmit impulses slower, do not have nodes of ranvier
89
why are synapses unidirectional
because only the presynaptic membrane has vesicles that releases neurotransmitter into the synapse and only the post synaptic membrane has receptors for the neurotransmitter
90
91
explain the stages of a nerve impulse
the first stage is known as the depolarisation then repolarisation then the recovery period
92
what is known as the resting potential
the potential difference across the membrane of an axon when an impulse not being transmitted
93
explain what it means when a neurone is polarised
this means that the inside of an axon is negatively charged (-70mv)
94
explain what it means in a polarised neurone
this means that there are more sodium ions on the outside of the axon and more potassium ions inside
95
how is the resting potential membrane
by the membrane being more permeable to the loss of potassium ions than intake of sodium ions and the sodium potassium pump actively transporting the ions
96
describe what happens in a nerve impulse
* when a receptor is stimulated above its threshold this causes an action potential to be generated and a nerve impulse is transmitted
* an action potential results in a change in the potential across axon membrane from -70mv to +40mv.
* this is known as depolarisation
* depolarisation occurs when there is a change in the permeability of the axon membrane to sodium ions as sodium channel proteins in the membrane open. this causes sodium ions to diffuse down a concentration gradient into the cell carrying positive charge
* the axon becomes depolarised
* when the axon is fully depolarised, the sodium channels close and potassium channels open up because the permeability of the membane to sodium ions decreases
* potassium gates open and potassium diffuses out of the cell taking positive charge with it
* this makes the inside less positive and repolarisation occurs
* during the recovery period, potassium ions move back into the cell through non volatage gated channels due to sodium potassium pump
* resting potential equilibrium restored
97
explain what happens at saltory conduction
this is when the nerve impulses travel faster than without myelin as they jump from one node to the next
98
explain the transmission at synapse
* action potential arrives
* membrane depolarises, calcium ions channels open and calcium ions eneter the neuron
* synaptic vesicles contain neurotransmitter fuse with presynaptic membrane due to calcium ions
* neurotransmitter releases into the synaptic cleft
* binds with receptors on postsynaptic membrane.
* sodium channels open and sodium ions flow through the channels
* membrane depolarises and action potential initiated
* neurotrans will be taken up across presynaptic membrane or diffuse and be broken down
99
where is acetylcholine made
in the brain
