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Biology AS > 1.2 > Flashcards

1.2 Flashcards

1
Q

Cell theory states?

A

all organisms are composed of cells; the cell is the basic
unit of life.

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2
Q

Organisms?

A

can be unicellular, such as amoeba and bacteria, or multicellular such as
plants and animals.

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3
Q

How do new cells arise?

A

from pre-existing cells; specialised cells arise from undifferentiated
stem cells.

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4
Q

Eukaryotic cells?

A

have a nucleus and membrane bound organelles.
Eukaryotic cells include
plant and animal cells.

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5
Q

Plant cells?

A

have additional organelles and structures e.g. chloroplasts for photosynthesis
and cellulose cell walls for support and to maintain turgor pressure.

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6
Q

Nucleus?

A

Contains DNA which codes for or controls protein synthesis.
DNA replication occurs here.
Transcription produces mRNA
templates.

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7
Q

Nuclear pores?

A

Allow the transport of mRNA and ribosomes out of the
nucleus.

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8
Q

Nuclear envelope
or double
membrane?

A

Separates the contents of the nucleus from the cytoplasm.

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9
Q

Nucleolus?

A

Produces rRNA, tRNA and ribosomes

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10
Q

Chromatin?

A

Condenses before cell division to form chromosomes.

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11
Q

Rough endoplasmic
reticulum?

A

Packaging and storing proteins. Producing transport vesicles
which merge to form the Golgi body.

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12
Q

Smooth
endoplasmic
reticulum?

A

Produce, package and transport steroids and lipids.

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13
Q

Golgi body/
apparatus?

A

Packaging proteins for secretion from the cell. Modification
of proteins e.g. by adding carbohydrate chains to form
glycoproteins.
Producing lysosomes and digestive enzymes
(tertiary structure).

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14
Q

Lysosomes?

A

Contain powerful digestive enzymes to break down worn
out organelles or cells. Phagocytes use lysosomes to digest
engulfed bacteria.

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15
Q

Centrioles?

A

Form the spindle during cell division.
They are not present in
higher plant cells.

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16
Q

Mitochondria?

A

ATP synthesis by aerobic respiration.

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17
Q

Chloroplasts?

A

Contain photosynthetic pigments which trap light energy for
photosynthesis.

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18
Q

Vacuole?

A

Contains cell sap and stores solutes such as glucose. Swells
due to osmosis for turgidity

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19
Q

Ribosomes?

A

Protein synthesis. Primary protein structure is formed at the
ribosome.

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20
Q

Plasmodesmata?

A

Connects cells via cytoplasm filled canals, which pass through
cell walls.
Allows transport via the symplastic pathway.

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21
Q

Cell wall?

A

Mechanical strength due to the high tensile strength of
cellulose microfibrils. Transport of solutes via the apoplastic
pathway.
Cell to cell communication via the plasmodesmata

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22
Q

Protein synthesis and excretion?

A

Ribosomes are produced in the nucleolus; they leave the nucleus via the nuclear
pores and take up their positions on the rough endoplasmic reticulum (ER).
The nuclear pores also allow mRNA molecules (formed from DNA templates by
transcription) to leave the nucleus. The mRNA molecules attach to the ribosomes
on the rough ER.
Protein synthesis takes place at the ribosome. The mRNA molecule contains
the code for the primary structure of a protein; the order of amino acids in a
polypeptide chain.
The rough ER transports the polypeptides via transport vesicles, which merge with
the Golgi body.
The polypeptides are modified in the Golgi body and converted to their tertiary
structure e.g. enzymes.
The enzymes are packaged into secretory vesicles and transported to the cell
membrane.
The secretory vesicles merge with the cell membrane and release the enzymes by
exocytosis.

23
Q

Similarities between mitochondria and chloroplast?

A

Both have double membrane
Both have highly folded inner membranes
Both have a circle of DNA for self-replication
Both have ribosomes
Both produce ATP

24
Q

Differences between them?

A

Mitochondria have cristae, but chloroplasts have thylakoid membranes.
Chloroplasts contain photosynthetic pigments to absorb light energy, mitochondria
do not.
Mitochondria have an inner matrix, but chloroplasts have a stroma.

25
Q

Bacteria?

A

Bacteria do not have membrane bound organelles in their cells – no nucleus, rough
endoplasmic reticulum, Golgi apparatus, mitochondria or chloroplasts; these cells are
prokaryotic cells.

26
Q

Prokaryotic cells?

A

Small cells
Ribosomes smaller and free in cytoplasm
No membrane bound organelles
DNA = free in cytoplasm
no nuclear envelope ( double membrane)
plasmids present
cell wall = peptidoglycen
No mitochondria - uses a mesosome

27
Q

Mesosome?

A

folded region of the cell membrane for aerobic respiration

28
Q

Eukaryotic cells?

A

Larger cells 10-100 µm
Ribosomes larger and bound to the rough
endoplasmic reticulum
Membrane bound organelles are present
DNA contained within the nucleus
Nucleus has a double membrane
No plasmids
cell wall when present = made of cellulose
Mitochondria = used for aerobic respiraition - there is no mesosome

29
Q

Viruses?

A

do not fit the cell theory
have no cell membrane, no cytoplasm, no organelles and no chromosomes
can only reproduce with the help of a host cell
they are composed of a protein coat or caspd when surrounds DNA RNA or simply a few genes the HIV virus has only 9 genes

30
Q

Atoms to systems?

A

Atoms = arranged into molecules
molecules form cells
cells work together to form tissues
tissues form organs and organs form systems

31
Q

Tissue defintion?

A

group of similar cells working together to perform a particular function

32
Q

Epithelial tissue?

A

type of tissue that forms a continous layer
covering or lining external surfaces of the body
Epithelia - no blood vessels
may have nerve endings
cells sit on a basement membrane, made of collagen and protein
vary in shape and complexity
often have protective or secretory function

33
Q

Cuboidal epithelium?

A

lines the kidney tubules and the small intestine
cube shaped

34
Q

Ciliated epithelium?

A

composed of cells which transport substances like mucus in the bronchi and ova in the fallopian tube
cilia moce and sweep substances along
cells = columnar - look like columns

35
Q

Squamous epithelium?

A

consists of flattened cells on a
basement membrane. They form the walls of the alveoli and
line Bowman’s capsule in the kidney nephron.

36
Q

Muscle tissue?

A

comes in 3 main types

37
Q

Skeletal muscle?

A

attatched to bones and moves skeleton
bands of long cells called fibres which contract powerfully but tire easily
voluntary muscles - you can choose whether to contract or not
Fibres form striped pattern which can be viewed under microscope why they are either referred to as sriped or striated muscle

38
Q

Smooth muscle?

A

smooth muscle has individual spindle shaped cells that can contract that can contract rhymthically but less powerfully than skeletal muscle
Occur in skin but walls of blood vessels and in digestive and respiratory tracts.
You cannot control these muscles - involuntary muscles
do not have stripes and are also called unstriped or unstriated muscle

39
Q

Cardiac muscle?

A

is only found in the heart. Its structure and
properties are somewhat in between skeletal and smooth
muscle.
The cells have stripes, but lack the long fibres of
skeletal muscle.
They contract rhythmically, without any
stimulation from nerves or hormones, although these can
modify their contraction. Cardiac muscle does not tire.

40
Q

Connective tissue?

A

connect,
support or separate tissues
and organs.
It contains elastic
and collagen fibres in an
extracellular fluid or matrix.
Between the fibres are fat
storing cells (adipocytes) and
cells of the immune system.

41
Q

Areolar tissue?

A

found under the skin and connects organs
and tissues together.

42
Q

Collagen?

A

forms tendons which connect muscles to bones.

43
Q

Ligaments?

A

which connect bones are elastic tissues.

44
Q

Adipose tissue?

A

composed of fatty cells and is found justunder the skin and around organs. It functions as an energy
store, thermal insulator and protects delicate organs.

45
Q

What are organs comprised of?

A

several tissues working together, performing a specific function

46
Q

Organ systems?

A

groups of organs working together with a particular role. Some examples
of mammalian organ systems are shown in the table.

47
Q

Calculating true size of structure from a magnified image?

A

Measure the A to B with a ruler in mm.
Divide this by the magnification (this will be given in the question, but is x 50000 in
this case).
Then multiply by 1000 to convert mm to μm.
Remember to give your answer to 3 significant figures.

48
Q

SI?

A

Système Internationale, the system which defines which units are used for
scientific communication

49
Q

Kilometre?

A

km
0.001
10^3 number of metres
Ecosystems

50
Q

Metre?

A

m
1
1
Larger
organisms

51
Q

Millimetre

A

mm
1000
10^-3
Tissues

52
Q

Micrometre?

A

µm
1 000 000
10^-6
Cells and
organelles

53
Q

Nanometre?

A

nm
1 000 000 000
10^-9 Molecules

54
Q

Units to remember?

A

1000nm = 1 µm
1000 µm = 1mm
1000 nm = 1m
1000 m = 1km

Biology AS (12 decks)

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