A2 Biology OCR June 2015 Revision Thread

Something weird:In the OCR Heinemanne book it says that by responding to external stimuli it helps the plant to 'avoid stress or to avoid being eaten'What? How can it cause help the plant to avoid being eaten?

Reply 3901

peanutcracker20

2

Original post by tewas

Adv: -animals with desirable characteristics can be produced eg high milk yield
- rare species on the verge on extinction can be preserved
- genetically engineered organisms can be produced quickly

Dis: - little genetic variation - more susceptible to environmental conditions/disease
- nobody knows long term health implications
- animal welfare issues hardly ever taken into account

thank you

Reply 3902

baymax96

2

so emotionally drained bc of this exam my body can't take anymore

Reply 3903

loperdoper

15

Original post by Shostakovish

Something weird:In the OCR Heinemanne book it says that by responding to external stimuli it helps the plant to 'avoid stress or to avoid being eaten'What? How can it cause help the plant to avoid being eaten?

Can emit chemicals that smell toxic to put predators off.

Reply 3904

Mansour

2

Original post by Maham88

can someone help me on q2a https://84a2c6735211cb85ba2409546df4f5700c55efef.googledrive.com/host/0B1ZiqBksUHNYSU00UmM3UFotQ0k/June%202010%20QP%20-%20Unit%205%20OCR%20Biology.pdf

You have to use your knowledge about Dominant and recessive epistatis,

for the first bit Its Dominate V so you move down one through the V then its A dominant C so you move another one and then finally a Dominant B, Where you arrive on red which is the phenotype expressed.

Same thing for the others as well but for the second one you can see that its recessive first so you stop there. there is no other route after that.

Reply 3905

Shostakovish

12

Original post by Maham88

can someone help me on q2a https://84a2c6735211cb85ba2409546df4f5700c55efef.googledrive.com/host/0B1ZiqBksUHNYSU00UmM3UFotQ0k/June%202010%20QP%20-%20Unit%205%20OCR%20Biology.pdf

This is epitasis (I think I spelt that right)
I think it is this
1) VvCcBb - so, dominant V, so it has intermediate compound one
Dominant C - so it has intermediate compound 2
Dominant B - so it is ultimately red
2)vvCCBB - no dominant v, so it is vermillion
3) VvccBB - Dominant V so it has intermediate compound 1
Recessive (not dominant) c, so it is cinnabar

Reply 3906

Mansour

2

Original post by Shostakovish

Something weird:In the OCR Heinemanne book it says that by responding to external stimuli it helps the plant to 'avoid stress or to avoid being eaten'What? How can it cause help the plant to avoid being eaten?

Release of chemical's to deter the organism(s) that are trying to place stress or are attempting to eat it.

Reply 3907

HeyThereHarry

16

All I know about eutrophication is that it's when sewage water adds additional nutrients, increasing growth rate. Is there anything more I should know?

Posted from TSR Mobile

Reply 3908

baymax96

2

Original post by Shostakovish

Something weird:In the OCR Heinemanne book it says that by responding to external stimuli it helps the plant to 'avoid stress or to avoid being eaten'What? How can it cause help the plant to avoid being eaten?

curling it's leaves

Reply 3909

Maham88

2

Original post by Shostakovish

This is epitasis (I think I spelt that right)
I think it is this
1) VvCcBb - so, dominant V, so it has intermediate compound one
Dominant C - so it has intermediate compound 2
Dominant B - so it is ultimately red
2)vvCCBB - no dominant v, so it is vermillion
3) VvccBB - Dominant V so it has intermediate compound 1
Recessive (not dominant) c, so it is cinnabar

oh okay, thank you !

Reply 3910

Mansour

2

Original post by domcandrews

What are the ratios we should know for genetics?

The ones for epistatsim, but you can work it out from the punnett square

Reply 3911

Shostakovish

12

Original post by loperdoper

Can emit chemicals that smell toxic to put predators off.

Thank you so much!
May you be granted a life of happiness

Reply 3912

NatRichmond

join this chat...we are discussing stuff and answering questions and ****. it pretty decent

Reply 3913

buxtonarmy

6

Original post by NatRichmond

join this chat...we are discussing stuff and answering questions and ****. it pretty decent

link pls

Reply 3914

tewas

2

please can someone help me on question d) on the chi-squared test spread in the OCR Heineman Textbook?

Reply 3915

plumpOlhenry

1

Every 1 look at wheat fam

Reply 3916

hermiones

3

Animals learning to relate a pair of events and respond to the first in anticipation of the second - it's passive and involuntary (Just think of the dog food and the bell) :-)

Reply 3917

ooxbridge

6

Original post by bakedbeans247

This is what i've heard people have been saying and what i think hasn't come up for a while:

galapagos,
something out of the topic about pcr/genome sequencing/insulin/rice etc,
something out of the pages 232, 236-237 (muscles topic),
brain
shedding leaves (pg 223)
how auxins stimulate shoot growth (pg 222)
meiosis
apoptosis
epistasis
something out of the topic animal behaviors (social behavior in primates i think)
Chi squared
Nitrogen cycle
Aseptic techniques/Asepsis - that table on the bottom of pg 163
Timber management

but anything could come up

even repeated topics