SB1 - KEY CONCEPTS IN BIOLOGY Flashcards
(109 cards)
1
Q
all living organisms can be grouped of ‘classified’ using the classification system that consists of five kingdoms. these five kingdoms are:
A
- animals
- plants
- fungi
- protoctists
- prokaryotes
2
Q
kingdoms containing eukaryotic organisms (4)
A
- animals
- plants
- fungi
- protoctists
3
Q
features of eukaryotes (2)
A
- can be multicellular or single-celled
- made up of cells that contain a nucleus bound by a distinct membrane
4
Q
features of prokaryotes (3)
A
- always single-celled
- do not contain a nucleus (instead, the nuclear material is found in the cytoplasm)
- prokaryotic cells are substantially smaller than eukaryotic cells
bacteria are prokaryotic organisms
5
Q
main features of animals (8)
A
- multicellular
- cells contain a nucleus with a distinct membrane
- cells do NOT have cellulose cell walls
- cells do NOT contain chloroplasts (so unable to carry out photosynthesis)
- feed on organic substances made by other living things
- often store carbohydrates as glycogen
- usually have nervous coordination
- able to move from place to place
6
Q
cell structures found in animal cells (5)
A
- nucleus
- cytoplasm
- cell membrane
- ribosomes
- mitochondria
7
Q
function of the nucleus
A
- contains the genetic material (DNA) which controls the activities of the cell
8
Q
function of cytoplasm
A
- a gel-like substance composed of water and dissolved solutes
- supports internal cell structures
- site of many chemical reactions, including anaerobic respiration
9
Q
function of cell membrane
A
- holds the cell together, separating the inside of the cell from the outside
- controls which substance can enter and leave the cell
10
Q
function of ribosomes
A
- found in the cytoplasm
- site of protein synthesis
11
Q
function of mitochondria
A
- site of most of the reactions involved in aerobic respiration, where energy is released to fuel cellular processes
** energy is RELEASED not made ** - cells with high rates of metabolism (carrying out many different cell reactions) have significantly higher number of mitochondria than cells with fewer reactions taking place
12
Q
main features of plants (7)
A
- multicellular
- cells contain a nucleus with a distinct membrane
- cells have cell walls made out of cellulose
- cells contain chloroplasts (so they can carry out photosynthesis)
- they feed by photosynthesis
- store carbohydrates as starch or sucrose
- do not have nervous coordination
13
Q
cell structures found in plant cells (8)
A
- nucleus
- cytoplasm
- cell membrane
- ribosomes
- mitochondria
+ - cell wall
- chloroplasts
- permanent vacuole
14
Q
function of cell wall
A
- made of cellulose (a polymer of glucose)
- gives the cell extra support, defining its shape
15
Q
function of chloroplasts
A
- contains green chlorophyll pigments (to absorb light energy) and the enzymes needed for photosynthesis
16
Q
function of permanent vacuole
A
- contains cell sap; a solution of sugars and salts dissolved in water
- used for storage of certain materials
- also helps support the shape of the cell
17
Q
main features of fungi (9)
A
- usually multicellular but some (eg. yeast) are single-celled
- multicellular fungi are mainly made up of thread-like structures known as hyphae that contain many nuclei and are organised into a network known as a mycelium
- cells contain a nucleus bound by a distinct membrane
- cells have cell walls made of chitin
- cells do not contain chloroplasts (so cannot carry out photosynthesis)
- feed by secreting extracellular digestive enzymes onto the food (usually decaying organic matter) then absorbing the digested molecules
- some fungi are parasitic and feed on living material
- some fungi store carbohydrates as glycogen
- do not hav coordination
examples of fungi include: moulds, mushrooms, yeasts
18
Q
cell structures found in fungi (6)
A
- nucleus
- cytoplasm
- cell membrane
- ribosomes
- mitochondria
+ - cell wall (containing chitin, not cellulose)
19
Q
main features of protoctists (7)
A
- a very diverse kingdom of organisms that don’t really belong in any of the other eukaryotic kingdoms
- mainly microscopic and single-celled but some aggregate (group together) into larger forms
- cells contain a nucleus bound by a distinct membrane
- some have features making them more like animal cells, some have features making them more like plant cells
- some protoctists photosynthesis, some feed on organic substances made by other living things
- do not have nervous coordination
20
Q
cell structures found in protoctists
A
- nucleus
- cytoplasm
- cell membrane
- ribosomes
- mitochondria
+ - food vacuole
- contractile vacuole
21
Q
the nuclear material of prokaryotic cells is found in the _________
A
cytoplasm
22
Q
prokaryotes are too small to contain __________ or ____________
A
chloroplasts or mitochondria
23
Q
bacteria are (prokaryotic/eukaryotic) organisms
A
prokaryotic
24
Q
features of bacteria (6)
A
- microscopic single-called organisms
- possess a cell wall (made of peptidoglycan, not cellulose), cell membrane, cytoplasm and ribosomes
- lack a nucleus but contain a circular chromosome of DNA that floats in the cytoplasm
- plasmids are present in prokaryotes; small rings of DNA (also floating in the cytoplasm) that contain extra genes to those found in the chromosomal DNA
- lack mitochondria, chloroplasts and other membrane-bound organelles found in eukaryotic cells
- some bacteria also have a flagellum or several flagella; long, thin, whip-like tails that allow them to move
25
specialised cells definition
cells that have developed certain characteristics (adaptations) in order to perform particular functions
26
cells specialise by undergoing _______________
differentiation
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describe what happens during differentiation
a process where cells develop the structure and characteristics needed to be able to carry out their functions
28
examples of specialised cells in animals (3)
- sperm cells
- egg cells
- ciliated epithelial cells
29
function of a sperm cell
reproduction: to carry the DNA of the male to the egg cell (ovum) of the female
30
adaptations of a sperm cell (4)
- head contains the genetic material for fertilisation in a haploid nucleus (containing half the normal number of chromosomes)
- the acrosome in the head contains digestive enzymes so that a sperm can penetrate an egg
- the mid-piece is packed with mitochondria to release energy needed to swim and fertilise the egg
- the tail enables the sperm to swim
31
function of an egg cell
reproduction: to be fertilised by a single sperm and develop into an embryo
32
adaptations of an egg cell (3)
- contains a lot of cytoplasm which has nutrients for the growth of the early embryo
- haploid nucleus contains half the genetic material for fertilisation
- cell membrane changes after fertilisation by a single sperm so that no more sperm can enter
33
function of ciliated epithelial cells
wafting bacteria and other particles (trapped by mucus) up to the throat (to be coughed out) or down to the stomach (to be digested)
34
adaptations of a ciliated epithelial cell (1)
- extensions of the cytoplasm at the surface of the cell form hair-like structures called cilia which beat to move mucus and trapped particles up to the throat
35
the first microscopes were discovered in the __th century
17th century
36
the first cells were observed by ______ _____ in 1665 using a _____ _________
Robert Hooke, light microscope
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with a modern light microscope, it is possible to see images of _____
cells and large sub cellular structures (like nuclei and vacuoles)
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______ are often required to highlight certain parts of cells when using a light microscope
stains
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maximum magnification of light microscopes
approximately 1000-2000x
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the first electron microscopes were developed in the 19__s
1930s
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electron microscopes use ______ __ _________, rather than light, to visualise specimens
beams of electrons
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electron microscopes have a (higher/lower) resolution and magnification than a light microscope
higher
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with an electron microscope, it is possible to see images of _____
many more sub cellular structures such as mitochondria, chloroplasts and ribosomes
44
maximum magnification of an electron microscope
2,000,000x
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magnification formulas (2)
magnification = image size / actual size
magnification = magnification of eyepiece lens x magnification of objective lens
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components of a microscope
- eyepiece lens (where you put your eye)
- objective lens (closest to the specimen, have low/medium/high power)
- stage (microscope slide is placed here)
- light source (mirror underneath specimen)
- coarse focus (focuses the low and medium power objective lenses) and fine focus (focuses the high power objective lens)
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commonly used stains
- methylene blue to stain cheek cells
- iodine to stain onion cells
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[microscopy] to prevent cells from being damaged by dehydration you can
add a drop of water to the specimen (beneath the coverslip)
49
limitations of optical microscopes (3)
- size of cells may appear inconsistent; cell structures are 3d and different tissue samples have been cut at different planes)
- optical microscopes have lower magnification power than other types of microscopes; there are some structures that cannot be seen
- treatment of specimens when preparing slides could alter the structure of cells
50
1m = _mm
1m = 1000mm
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1mm = _μm
1mm = 1000μm
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1μm = _nm
1μm = 1000nm
53
enzymes are _______
- proteins that act as biological catalysts to speed up the rate of a chemical reaction without being changed or used up
- they are made in living cells
- enzymes are necessary to all living organisms as they allow all metabolic reactions to occur at a rate that can sustain life
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enzymes are ________ to one particular substrate
specific
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the active site of the enzyme is where _______
the substrate attaches
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active sites are a _____________ shape to the substrate
complementary
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steps of an enzyme catalysed reaction
1. enzyme and substrates randomly move about in solution
2. when an enzyme and its complementary substrate randomly collide, an enzyme-substrate complex forms and the reaction occurs
3. a product forms from the substrate and is then released from the active site. the enzyme is unchanged and will go on to catalyse further reactions
58
if the bonds that hold the enzyme together are disrupted or broken the enzyme is _________
denatured; the active site loses its shape
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enzyme denaturation is (reversible/irreversible)
irreversible; once enzymes are denatured they cannot regain their proper shape and the reaction they are catalysing will stop
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conditions that cause enzymes to denature (2)
- high temperatures
- extremes of pH
61
enzymes work fastest at their _______ temperature
optimum
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in the human body, the optimum temperature is about __°C
37°C
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low temperatures (do/do not) denature enzymes
low temperatures do not denature enzymes
- they just make them work more slowly due to a lack of kinetic energy
64
as temperature increases (towards the optimum), activity of enzymes _________
increases (more kinetic energy -> more collisions)
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as temperature increases (beyond the optimum), enzymes ________
denature
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factors affecting enzyme action (3)
- temperature
- pH
- substrate concentration
67
as substrate concentration increases, activity of enzymes _________
- increases to a point; likelihood of enzyme-substrate complex formation increases
- however all available active sites eventually become saturated and enzyme activity will PLATEAU
68
rate of reaction formula
rate = change / time
OR
rate = amount of substrates used or product formed / time
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rate of reaction formula IF not told how much something has changed
rate = 1 / time
70
the purpose of digestion is _______
to break down large, insoluble food molecules into smaller, soluble molecules that can be absorbed into the bloodstream
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carbohydrases are a group of enzymes that break down ______ into _______
carbohydrates -> simple sugars eg. glucose
72
example of a carbohydrase (1)
amylase
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amylase is made in the _______ (3)
- salivary glands
- pancreas
- small intestine
74
amylase breaks down ______ into _______
starch -> glucose
75
proteases are a group of enzymes that break down ________ into _____ _____
proteins -> amino acids
76
example of a protease (1)
pepsin
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pepsin is made in the _______ (1)
stomach
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lipases are enzymes that break down ______ to ________ and _____ _____
lipids (fats) -> glycerol and fatty acids
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lipase enzymes are produced in the ________ and secreted into the _____ _________
pancreas, secreted into small intestine
80
carbohydrates are synthesised by joining ______ ______ together
simple sugars
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proteins are synthesised by joining _____ _____ together
amino acids
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lipids are synthesised by joining _____ _____ or ________
fatty acids or glycerol
83
describe the food test for glucose/reducing sugars
- add benedict’s solution to the sample solution in a test tube
- heat in a boiling water bath for 5 minutes
- a positive test will show a colour change from blue -> orange or brick red
84
describe the food test for starch
- add drops of iodine solution to the food sample
- a positive test will show a colour change from orange-brown -> blue-black
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describe the food test for protein
- add drops of biuret solution to the food sample
- a positive test will show a colour change from blue -> violet/purple
86
describe the food test for lipids
- mix the food sample with ethanol and shake
- allow time for the sample to dissolve in the ethanol
- strain the ethanol solution into another test tube
- add the ethanol solution to an equal volume of cold distilled water
- a positive test will show a cloudy emulsion forming
87
describe a simple calorimetry experiment
- pour water into a boiling tube and record it’s starting temperature
- weigh the initial mass of the food sample
- set fire to the sample of food using a bunsen burner and hold the sample 2cm from the boiling tube u tik it has completely burned
- record the final temperature of the water
- weigh the mass of any remaining food
88
limitations of a calorimetry experiment
- incomplete burning of the food sample
- heat energy is lost to the surroundings
89
ways for substances to move in and out of cells (3)
- diffusion
- osmosis
- active transport
90
diffusion is ______
- the movement of molecules from a region of higher concentration to a region of lower concentration
- molecules move down a concentration gradient
91
in diffusion, molecules move (up/down) a concentration gradient
down
92
describe cell membrane permeability
partially permeable:
smaller molecules can diffuse across the membrane but larger molecules cannot
93
examples of diffusion in living organisms (6)
- small intestine: digested food products diffuse from small intestine to blood
- leaf: oxygen diffuses from air spaces between mesophyll cells to mitochondria in all cells
- leaf: carbon dioxide diffuses from air spaces between mesophyll cells to chloroplasts in mesophyll cells
- leaf: water vapour diffuses from stomata to air outside stomata
- lungs: oxygen diffuses from alveolar air space to blood in capillaries around alveoli
- lungs: carbon dioxide diffuses from blood in capillaries around alveoli to alveolar air space
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factors that influence diffusion
- surface area : volume ratio
- diffusion distance
- temperature
- concentration gradient
95
diffusion is a form of (active/passive) transport
PASSIVE transport
96
osmosis definition
the movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane
97
osmosis is a form of (active/passive) transport
PASSIVE transport
98
water can move in and out of cells by _______
osmosis
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osmosis occurs (up/down) a concentration gradient
down
100
a concentrated solution has a ___ water potential
low
101
a dilute solution has a ____ water potential
high
102
describe red blood cells in a hypertonic solution
- red blood cells have HIGHER water potential than solution
- water moves out of cells
- cells shrivel up
103
describe red blood cells in an isotonic solution
- water potential EQUAL between red blood cell and solution
- no net movement of water
- normal cells
104
describe red blood cells in a hypotonic solution
- red blood cells have LOWER water potential than solution
- water moves into cells
- cells swell, may lose (burst)
105
why are plant cells protected from cell lysis?
they have a supporting cell wall whereas animal cells don’t
106
percentage change in mass formula
(final mass-initial mass) / initial mass
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active transport definition
the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration
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energy is needed for active transport because ______
cells are moving against a concentration gradient, in the opposite direction from which they would naturally move (by diffusion)
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examples of active transport
- allows glucose to be transported into the blood stream from the small intestine when the concentration of sugar molecules in the blood is higher
- allows root hair cells in plants to move minerals such as magnesium ions from a region of lower concentration (the soil) to a region of higher concentration ( the cytoplasm of the cell)
