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b2 Flashcards

1
Q

why are new cells needed?

A

for growth and repair

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2
Q

what is the cell cycle?

A

where cells grow and divide repeatedly

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3
Q

why do cells in your body divide?

A

produce more cells so your body can grow and replace damaged cells.

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4
Q

what’s it called when cells grow and divide repeatedly?

A

The cell cycle

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5
Q

what sub-categories is interphase divided into?

A

G1
S (synthesis)
G2

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5
Q

what is the first stage of cell cycle?

A

Interphase
the cell grows and replicates its DNA in preparation for division

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5
Q

what is G1 in the cell cycle?

A

The cell grows and carries out its normal metabolic functions, and prepares for DNA synthesis

GAP PHASE 1

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6
Q

how is DNA replicated?

A

.DNA unzips
.complimentary base-pairing

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7
Q

what is G2 in the cell cycle?

A

The cell continues to grow and prepare for cell division

GAP PHASE 2

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7
Q

what is S phase in the cell cycle?

A

The cell synthesizes a copy of its DNA, which is replicated during this phase

SYNTHESIS

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8
Q

what is Mitosis?

A

cell division which produces two identical diploid daughter cells

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8
Q

steps of mitosis
starting with the cell having 2 copies of its DNA?

A

.DNA spread out
.DNA forms x chromosomes
.Chromosomes LINE up in middle
.x is pulled apart to OPPOSITE ends
.membrane forms around each side - surrounding chromosomes
.CYTOKINISIS - cytoplasm divides
.
.no have 2 genetically identically diploid daughter cells

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9
Q

What is the second stage of the cell cycle?

A

Mitosis
cell divides into 2

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10
Q

what is cytokinesis?

A

stage during which the cell physically divides into two daughter cells

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11
Q

what is the third stage of the cell cycle?

A

CYTOKINISIS

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12
Q

what is differentiation?

A

process by which a cell changes to become specialised to its job

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13
Q

why is having specialised cells good?

A

allows organisms to work more efficiently

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14
Q

what is the palisade leaf cells?

A

SPECIALISED CELL
.do most of photosynthesis
.packed with chloroplasts
.TALL shape = large SA exposed down side for absorbing CO2
.THIN shape means can fit loads on top of a leaf, nearer to the light

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15
Q

what is the sperm cell?

A

SPECIALISED CELL
.get male DNA to female DNA during reproduction
.LONG tails and STREAMLINED heads help them swim
.contain a lot of mitochondria provide them with energy
.enzymes in their head to digest through egg cell membrane

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16
Q

What are stem cells?

A

undifferentiated cell of an organism which is capable of dividing by mitosis

those new cells then can differentiate

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17
Q

what are Embryonic stem cells?

A

found in early embryos and are completely undifferentiated.

This means that they can be used to turn into any type of cell.

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18
Q

what are adult stem cells, where are they found?

A

Stem cells can be found in the bone marrow, teeth and other areas.

These cells cannot differentiate into any type of cell

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19
Q

what are adult stem cells used for in animals?

A

replace damaged cells
-make new skin
-more blood cells

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20
Q

what are meristems?
What is the role of a meristem?

A

type of tissue found in plants

produce unspecialised cells that have the potential to become any type of specialised cell.

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21
what does meristem contain?
plant stem cells
22
where is meristem tissue found?
areas of plant that are growing ROOTS AND SHOOTS
23
what is diffusion?
NET movement of particles from an area of HIGH concentration to an area of LOW concentration
24
how can substances move in and out of cells?
diffusion active transport osmosis
25
what can diffuse through the cell membrane?
SMALL molecules glucose, amino acids, water and oxygen -starch and proteins CANNOT FIT
26
what is active transport?
the movement of substances AGAINST their concentration gradient using the ATP (energy) released during respiration
27
how does active transport work in the digestive system?
.high conc of nutrients in gut .diffuse naturally too blood .SOMETIMES .low conc of nutrients in gut .active transport allows nutrients to still be taken into blood even though conc gradient is the wrong way .stops us starving .NEEDS ATP from respiration to work
28
what is osmosis?
diffusion of water NET movement of water molecules across a partially permeable membrane from an area of high water potential to an area of low water potential
29
what is a partially permeable membrane?
membrane with SMALL holes in it. only tiny molecules like water can pass through it
30
how are plants supported?
turgid cells (plump and swollen)
31
what is turgor pressure?
the force exerted by water pushing against the cell wall of a plant cell
32
what happens to a plant if there is no water in the soil? why?
It will wilt .cells become flaccid inelastic walls still keep plant in position
33
what is the experiment for osmosis?
involves putting potato cylinders into diff conc of sucrose solution see what affect diff WP has .prep sucrose solutions of different concs .make potato cylinders all same size (1cm diameter) .divide potato into group of 3 WEIGH each group .place one group in each solution .leave cylinders in solution for at least 40 mins .remove cylinders and pat down WEIGH each group again .calculate % change in mass .plot a graph of results
34
independent variable of osmosis variable?
CHANGE concentration of the sucrose solution
35
control variable of osmosis experiment?
.volume of sucrose solution .size of potato cylinders .time potato in solution for
35
dependent variable of osmosis experiment?
MEASURE the change in mass of potato cylinder
36
what are the main factors that affect the movement of substances?
SA to volume ratio temperature conc gradient
37
why is diffusion harder in multicellular organisms?
.some cells are deep inside the organism .larger organisms have a lower SA : volume
38
why is diffusion quicker in single-cellular orgainsims?
.travel a short distance .higher SA : Volume
39
how do multicellular organisms diffuse?
.need specialised exchange organs each with a specialised exchange surface
40
how are exchange surfaces adapted to maximise exchange?
.THIN - short distance to travel .large SA - lots can move at once .in animals - lots of BLOOD VESSELS to get stuff in and out blood quickly .Ventilated -air moves in and out
41
where does gaseous exchange take place?
alveoli in lungs
42
what is gaseous exchange?
delivery of oxygen from the lungs to the bloodstream and the elimination of carbon dioxide from the bloodstream to the lungs and out of the body.
43
what is a villi?
found in the small intestine of the digestive system. They increase the surface area of the intestines to allow digested food to be efficiently absorbed into the bloodstream
43
how are alveoli specialised for gas exchange?
.large SA .THIN walls - 1 cell thick .MOIST walls .large blood supply
44
how are villi specialised?
.SINGLE layer of surface cells .good blood supply assist with quick absorption
45
what is the circulatory system made up of?
heart blood vessels blood
46
what is humans circulatory system like?
double
46
what happens in the first circuit (heart)?
heart pumps DEoxygenated blood to gas exchange surface in lungs to take in oxygen .oxygenated blood then returns to the heart
47
what happens in the second circuit (heart)?
heart pumps oxygenated blood around body. blood gives up its oxygen at body cells and deoxygenated blood returns to heart to be pumped to lungs again.
48
advantages of a double circulatory system?
.returning blood to heart after its got oxygen from lungs - means can be pumped around body at a HIGH PRESSURE .which increases rate of blood flow to tissue so more oxygen can be delivered to cells .important for mammals because they use a lot of oxygen maintaining body temp
49
parts of a heart?
.bicuspid, tricuspid VALVES .left, right atrium .left, right ventricle .aorta .pulmonary artery, vein .vena cava
49
what is the heart valves for?
make sure blood flows in the right direction .ventricles contract - tri/bicuspid valves close - semilunar valves open PREVENT BACKFLOW
50
how does heart use its 4 chambers? Start blood flowing into atria
flows into atria from vena cava and pulmonary vein .atria contract - put blood in ventricles .ventricles contract - put blood into pulmonary artery, aorta to go OUT heart .blood flows to organs through arteries - return through veins .atria fill - cycle repeats
50
what is heart made of?
cardiac muscle
51
what is an artery?
take blood AWAY from heart .high pressure .thick walls .small lumen
51
what is a vein?
take blood INTO the heart .large lumen .thin walls .low pressure .contain valves
52
what are capillaries?
involved in EXCHANGE OF MATERIALS .one cell thick walls .tiny lumen .gaseous exchange
52
what does blood consist of?
plasma platelets red blood cells white blood cells
52
what is plasma?
liquid it of blood .pale yellow liquid .carry everything e.g. -RBC, WBC, platelets -water -glucose, amino acids -CO2 -urea -hormones -antibodies
53
what are red blood cells?
transport oxygen from lungs to all cells in body .small with biconcave disc for a large SA: volume -haemoglobin - gives blood colour .NO nucleus, frees up space .small and flexible
54
what is a phloem?
transport food .made of columns of living cells called SIEVE TUBE elements .sieve - no nucleus cant survive on own - have a COMPANION cell. -which carry out living functions .FOOD UP and DOWN stem TRANSLOCATION
55
what is xylem?
takes water UP tube .dead cells joined end to end .thick side walls made of cellulose - strong and stiff for support .cell wall strengthen with lignin .carry water and minerals from roots TO shoots to leaves in TRANSPIRATION SYSTEM
56
what is transpiration?
loss of water from the plant .caused by evaporation and diffusion of water from a plants surface
57
benefits of transpiration stream on plants?
.constant stream of water from ground keeps plant cool .provides plant with constant supply of water for photosynthesis .water creates turgor pressure - support plant and stop wilting .minerals needed can be brought in from soil with water
58
what affects the rate of transpiration?
.LIGHT INTENSITY increase light, increases rate of transpiration .TEMPERATURE increase temp, increases rate of transpiration .AIR MOVEMENT lots of air, increases rate of transpiration
59
how do plants reduce water loss?
.leaves have a waxy cuticle covering the upper epidermis -makes upper surface of leaf WATERPROOF .stomata on lower surface of leaf - darker and cooler -slows down DIFFUSION of water out of leaf .bigger + more stomata more water plant loses -hot climate plant, need to CONSERVE water so have fewer and smaller stomata
60
how do stomata's work?
.close automatically when supplies of water start to dry up .thin outer walls, thick inner walls - means open and closing function works properly .open stomata allows gases in and out for photosynthesis -SENSITIVE to light, open during day and close a night - conserve water
61
what do you use to measure rate of water loss?
POTOMETER (transpirometer)
62
how is a potometer used?
.cut a shoot underwater (prevent air entering xylem) at a SLANT (↑ SA) .assemble potometer in water, insert shoot underwater .check apparatus is water/air tight .dry leaves, shut tap .remove end of capillary tube until one air bubble has formed, put tube back in water .record starting position .stopwatch - record distance moved by air bubble .calculate speed of air bubble
63
how can you see how environment conditions affect transpiration rate?
POTOMETER .measure transpiration (practical) adding different light intensity's, changing temp, adding more air .LAMP .HOT/COLDER room .FAN

biology (3 decks)

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