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Biology OCR AS Jess > Topic 4 > Flashcards

Topic 4 Flashcards

1
Q

What is cellulose?

A

A polysaccharide

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2
Q

What type of glucose is cellulose made from?

A

Beta glucose

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3
Q

What bonds do cellulose have?

A

1-4 glycosidic.

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4
Q

What angle does cellulose bond? Why?

A
  1. Straight unbranched strong structure.
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5
Q

What bonds neighbouring cellulose chains?

A

Hydrogen.

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6
Q

Where do the bonds form on cellulose chains

A

OH- of the OH of one and ch2oh of another.

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7
Q

What is the structure of the cell wall?

A

Microfibrils would around the cell in a helical arrangement at angles. Stuck by a polysaccharide glue.

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8
Q

What is the polysaccharide glue?

A

Short branched polysaccharides. Hemicelluloses and pectins.

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9
Q

What does the polysaccharide glue do? Properties once set

A

Binds to cellulose and each other. This holds microfibril together with strong and flexible properties.

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10
Q

What does pectin also do?

A

Hold adjacent plant cells together

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11
Q

What are the plasmodesmata?

A

Narrow fluid filled channels across cell walls. This make cytoplasm between cells continuous.

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12
Q

Where are the plasmodesmata located?

A

Pits between plant cells.

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13
Q

What do xylem vessels do?

A

Tubes that transport water and minerals. Also used as structural support

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14
Q

What do the sclerenchyma fibres do?

A

Provide support.

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15
Q

What do phloem sieve tubes do?

A

Transport organic solutes e.g. Amino acids and sugars.

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16
Q

What are the three types of tissue found within the plant? Where are they? Role?

A

Dermal tissue(outer layer), vascular tissue( centre) transport, ground tissue(middle layer) photosynthesis.

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17
Q

What does a vascular bundle contain?

A

Xylem, phloem,

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18
Q

What is on the edge of a vascular bundle?

A

Sclerenchyma fibres.

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19
Q

What tissue take up the majority of the stem?

A

Parenchyma

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20
Q

What lies on the outside on the stem?

A

Collenchyma tissue

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21
Q

How are the xylem made waterproof?

A

Lignin

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22
Q

What are the steps of transpiration?

A
  • water vapour diffuses through the stomata down the concentration gradient
  • water then evaporates from the surface cells in the sub-stomatal cavity. This makes up for the water lost through the stomata.
  • capillary action in cell walls replaces the water in these cells
  • water is drawn out of the xylem
  • a continuous column of water is draw up through the xylem.
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23
Q

Where does the energy to move water through plants come from?

A

The sun

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24
Q

What is the cohesion tension theory?

A

Tension is caused by the transpiration stream that pulls water up the xylem. The stream of water does not break due to cohesion, this is hydrogen bonds between water molecules.

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25
What do black dots signify on plants?
Magnesium deficiency
26
What does stunted growth suggest in plants?
Calcium deficiency.
27
What would a nitrogen deficiency look like in plants?
Yellow leafs.
28
What is translocation?
The transport of organic molecules within the phloem.
29
What is usually transported in translocation?
Sugar, amino acids from leafs.
30
What can the substances in the phloem lead to?
Root growth, buds, starch storage.
31
What else can travel in the phloem?
Viruses, growth regulators (hormones)
32
What is the role of the companion cell?
Contain the organelles needed to preform metabolic functions for the phloem sieve tube.
33
How do substances move in the phloem? Features of the cell?
Through transfer cells which have small unfolds to increase surface area. They also have plasmodesmata to link the cytoplasm of adjacent cells. Mitochondria for energy
34
How are substances transported in the phloem?
- Sucrose uses active transport to move from the leaf to the transfer cell, to the phloem. - due to the high solute concentration in the phloem water from the xylem moves to the phloem by osmosis. This creates a high pressure. - At the sink sucrose is unloaded by active transport. - due to a low solute concentration water moves back to the xylem by osmosis. This creates a low pressure. - the difference in pressure causes mass flow.
35
Where is the high and low pressure in the phloem?
High at loading end. Low at sink.
36
Uses of lignin?
Waterproof and strength.
37
What is a niche
The way an organism exploits its environment
38
What are the three types of adaptations
Behavioural, anatomical, physiological.
39
What is co adaptation
Organisms rely on eachother and adapt with eachother.
40
Evolution
A change in the allele frequency in a population over time
41
Evolution process
A population has a genetic variation and a new allel is created through mutations. A change in environment causes different selection pressures. This allel is now more favourable. Organisms with this allel will be more likely to survive and reproduce. This passes the allel to offspring. This increases allel frequency.
42
In the hardy Weinberg equation what does each letter represent
P is frequency of dominant gene | Q is frequency of recessive.
43
What are the two hardy Weinberg equations. | Method
P+q=1 P^2 + 2pq + q^2 =1 Usually given homozygous recessive percentage. Square root. Use p+q=1. You now and p and q. Input these into equation and read off requires percentage.
44
What does the hardy Weinberg equation show.
The change in allel frequency over time.
45
What does the ability to adapt depend on
Strength of selection pressure, size of gene pool, reproductive rate.
46
Speciation progress
Isolation due to a geographical feature such as mountain or river. This prevents the two groups of a species from breeding. Over time a new selection pressure will cause the groups to adapt due to random mutations being more favourable in the new environment. Eventually the two groups can not interbreed to produce fertile offspring so they are different species. The longer they are separated the more the allele frequency changes.
47
Is the Order genus then species as the lowest. Or species and genus as the lowest
Genus and species as lowest
48
Classification order
Kingdom. Phylum. Class. Order. Family genus. Species.
49
Diversity index equation
N(N-1) / total of n(n-1) Aka. (Total organisms X total org -1) / (individual speciesX individual -1)
50
What are amyloplasts
Storage vacuoles contains starch.
51
What are tonoplasts
Membrane of the vacuole
52
In cellulose where are the glycosidic bonds
Two OH. (180•)
53
What is autocytosis. What is made this way
Breaking of toniplasts and membranes | Xylem.
54
Are xylem and schlerchyma both lignified
Yes
55
What are the five stages of clinical trials
Pre clinical. Clinical phase 1,2,3. After licensing.
56
What happens in pre clinical trials
Lab Tests of cells and tissues to see effectiveness. This can take several years. Animal trial are also used
57
Clinical trail phase 1
Healthy volunteers tested at different dosages and to see if drug behaves how expected.
58
Clinical trial phase 2
Volunteers with disease to test effectiveness again. 100-300 people
59
Clinical trial phase 3
1000-3000. Double blinds trial. Compare results between two groups and this is the final safety test.
60
After licensing
Effectiveness and safety continually tested

Biology OCR AS Jess (4 decks)

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