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Edexcel 6BIO2 ~ 3rd June 2013 ~ AS Biology

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Reply 1720

Whostolemycookie

Original post by ramanan

Thanks that really puts me at ease, I wish you very good luck :wink:

Reply 1721

SyedaK

Original post by Chinensis8

What do you guys think will come out?
Panicking here! :eek:

I'm so worried over biology I had a dream about totipotency. That could come up. Dream doesn't mean anything but has it come up in a while?

Reply 1722

TheUndercoverPanda

Original post by Chinensis8

What do you guys think will come out?
Panicking here! :eek:

I feel like there could be a big fertilization question

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Reply 1723

Chinensis8

Original post by SyedaK

I'm so worried over biology I had a dream about totipotency. That could come up. Dream doesn't mean anything but has it come up in a while?

Ok Totiptency, I had slight dreams about cell walls. I'm so nervous I feel like an anorexic about to purge :s-smilie:

Original post by TheUndercoverPanda

I feel like there could be a big fertilization question

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Ok fertilization. *sigh* Anyone know anything about the difference in starch and cellulose and microfibrils?

Reply 1724

ramanan

Original post by Chinensis8

Ok Totiptency, I had slight dreams about cell walls. I'm so nervous I feel like an anorexic about to purge :s-smilie:

Ok fertilization. *sigh* Anyone know anything about the difference in starch and cellulose and microfibrils?

1. both made up of glucose / eq ;
2. both {have(1-4) glycosidic bonds / made by
condensation reactions} / eq ;
3. both have 1-4(glycosidic) bonds ;
4. starch is α glucose, cellulose is β glucose ;
5. starch composed of {more than one type of
molecule / amylose and amylopectin ;
6. correct reference to {branching / 1-6 bonds /
helix} in starch / straight chain in cellulose ;
7. all monomers same orientation in starch /
every other one inverted in cellulose ;

Reply 1725

Whostolemycookie

Original post by Chinensis8

Ok Totiptency, I had slight dreams about cell walls. I'm so nervous I feel like an anorexic about to purge :s-smilie:

Ok fertilization. *sigh* Anyone know anything about the difference in starch and cellulose and microfibrils?

Starch is alpha glucose and cellulose is beta glucose, microfibirils are bundles of cellulose molecules found in the cell walls of plants held together by pectin

Reply 1726

Chinensis8

Original post by ramanan

Original post by Whostolemycookie

Starch is alpha glucose and cellulose is beta glucose, microfibirils are bundles of cellulose molecules found in the cell walls of plants held together by pectin

Alright! Thanks~

Reply 1727

Whostolemycookie

What are the meaning to these keywords:
niche
ecosystem
species
species richness
genetic variation
population
habitat diversity
community
endemism

Reply 1728

Matterhorn

Original post by Chinensis8

Ok Totiptency, I had slight dreams about cell walls. I'm so nervous I feel like an anorexic about to purge :s-smilie:

Ok fertilization. *sigh* Anyone know anything about the difference in starch and cellulose and microfibrils?

Starch:

•

contains amylose and amylopectin joined by alpha glycosidic bonds.

•

Amylose = straight chained (due to 1,4 glycosidic bonds).

•

so it develops coiled structure (H bonds within chain forming helix) - more compact - more can fit in small space.

•

Amyloectin = branched (1,6 glycosdic bonds)

•

branches more easily hydrolysed, therefore quicker source of glucose to be used in respiration

•

Long polymer so insoluble

•

doesn't effect osmotic pressure of cell

•

Used for storage

Cellulose:

•

made of beta glucose monomers joined by beta glycosidic bonds

•

Straight chained

•

H bonds between chains forming microfibrils

•

microfibrils contain between 50-80 adjacent glucose chains

•

Also insoluble

•

Used for structural support

Reply 1729

Chinensis8

Original post by Whostolemycookie

What are the meaning to these keywords:
niche
ecosystem
species
species richness
genetic variation
population
habitat diversity
community
endemism

Here this could help.

Biology Unit 2 Topic 4 Summary.pdf343.9KB

Reply 1730

SyedaK

Original post by Chinensis8

Ok Totiptency, I had slight dreams about cell walls. I'm so nervous I feel like an anorexic about to purge :s-smilie:

Ok fertilization. *sigh* Anyone know anything about the difference in starch and cellulose and microfibrils?

Well all we can do is try!

From what I learnt:
Similarities:
Starch and Cellulose are both made of glucose
Both chains are linked together by 1,4 gylcosidic bonds

Differences:
Starch is a mixture of two polysaccharides (Amylose and Amylopectin)
Between 50 and 80 cellulose chains are linked together by large number of hydrogen bonds to from strong threads called microfibrils
Cellulose is unbranched long chain
Starch is coiled and branched

The cell wall contains cellulose micro-fibrils in a net like arrangement - the strength of microfibrils and their arrangement gives plants strength

Reply 1731

Rubyturner94

im so nervous :frown:

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Reply 1732

Chinensis8

Original post by SyedaK

Original post by Matterhorn

Starch:

•

contains amylose and amylopectin joined by alpha glycosidic bonds.

•

Amylose = straight chained (due to 1,4 glycosidic bonds).

•

so it develops coiled structure (H bonds within chain forming helix) - more compact - more can fit in small space.

•

Amyloectin = branched (1,6 glycosdic bonds)

•

branches more easily hydrolysed, therefore quicker source of glucose to be used in respiration

•

Long polymer so insoluble

•

doesn't effect osmotic pressure of cell

•

Used for storage

Cellulose:

•

made of beta glucose monomers joined by beta glycosidic bonds

•

Straight chained

•

H bonds between chains forming microfibrils

•

microfibrils contain between 50-80 adjacent glucose chains

•

Also insoluble

•

Used for structural support

Thanks~ I kinda blanked out when I saw the q on a past paper :s-smilie:

Reply 1733

Whostolemycookie

Original post by Chinensis8

Here this could help.

I can't see it because I don't have adobe reader, can you write it out for me :redface:

Reply 1734

Rubyturner94

2 hrs and 50 minutes till the exam.

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Reply 1735

SyedaK

Original post by Rubyturner94

im so nervous :frown:

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I get hungry when I'm nervous so I'm eating. Maybe you should eat something

Reply 1736

ramanan

guys here's some use full tip I found thought i might share them

when asked to explain a graph try write these
1.state whether it show positive or negative coorelation
2.Manupulate data
3.state liner non liner

also have a look at this qustion before u leave

plant tissue cuture
2010 jan 3c

best of luk to all gona sign out, 3hrs more

Lets hope for the best

Reply 1737

Matterhorn

Original post by Whostolemycookie

What are the meaning to these keywords:
niche
ecosystem
species
species richness
genetic variation
population
habitat diversity
community
endemism

Niche - role of organism within a habitat
Ecosystem - a biological community of interacting organisms and their physical environment.
Species - a group of similar (similar behaviourally, physiologically and anatomically) organisms that can interbreed to produce fertile offspring.
Species richness - number of species in a given habitat at a given time
Genetic variation - number of alleles in a gene pool of a species
Population -the number of organisms within a particular species.
Habitat diversity - the number of different types of habitats in a given area
Community - the various populations in an area.
Endemisms- organisms that live in one particular are/habitat.

Good luck today!

Reply 1738

Chinensis8

Original post by Whostolemycookie

I can't see it because I don't have adobe reader, can you write it out for me :redface:

Biodiversity the variety and variability among living organisms and the ecological complexes in which they occur
Species a group of organisms with similar morphology, physiology and behaviour, which can interbreed to produce fertile offspring and which are reproductively isolated from other species
Habitat place where an organism lives. Each habitat has a particular set of conditions which supports a distinctive combination of organisms
Population a group of interbreeding individuals of the same species found in an are
Community various populations in a community
Niche the way an organisms exploits its environment. If two species live in the same habitat and have the same role within the habitat (same food, time of feeding, shelter) they occupy the same niche and will compete.
Behavioural adaptions any actions by an organism which help them to survive and reproduce
Physiological adaptions features of the internal workings of an organism which help them to survive and reproduce
Anatomical features structures we can see when we observe or dissect an organism
Co-adaption when two organisms depend on each other to survive
Natural selection mechanism by which organisms change over time as they adapt to their changing environments
Hacking out animal being taken out into forest and gradually given more freedom and less food to encourage animals to feed for themselves
Reintroduction breeding animals in captivity that are returned to native habitat
Species richness Number of species ina given area
Genetic variation Number of allele in a gene pool of a species
Endemisms An organism that is found only in one area

I just copied and pasted it :0

(edited 10 years ago)

Reply 1739

Matterhorn

Quick question - can anyone run through the steps that lead to differential gene expression?