HSC Biology Marathon 2017 (1 Viewer)

[Green Yoda]

All questions so far seem to have been answered, so I'll throw another question in, if no one minds:

Describe the main changes in blood composition as it travels around the body and identify the tissues in which these changes occur. (5 marks ?) Not sure how much this would be worth o:

Blood moves the body around in two pathways knows as pulmonary circuit and systemic circuit. The pulmonary circuit is a circuit of blood between the lungs and the heart, so as the blood flows to the lungs there will a decrease in carbon dioxide and an increase in oxygen in the blood composition as these gases are diffused in the alveoli. The systemic circuit consists of a circulation of blood from the heart to all other body cells and organs. As the blood goes to body tissues there will be a decrease in oxygen and an increase in carbon dioxide in the blood composition as the tissues require oxygen and the waste product which is the carbon dioxide is diffused into the blood. As the blood circulates to the liver there will be a decrease in nutrients such as glucose and an increase in nitrogenous wastes in the blood as liver requires alot of energy due to high metabolic activity and diffuses the detoxified nitrogenous wastes into the blood. As the blood goes to the kidney there will be a decrease in Nitrogenous wastes from the blood and into the kidney which turns it into urea and is removed through urination. As the blood goes to the small intestine there will be a decrease in nutrients such as glucose and an increase in products of digestion in the blood stream as high amounts of energy is required in the small intestine as it has a function of digesting and absorbing food and as a result the products of digestion are diffused into the blood. As the blood circulates to the large intestine there will be an decrease in nutrients such as glucose and an increase in water salts in the blood composition as it has a function to absorb water from indigestible foods so it requires alot of energy to do so, thus the increase in salts and water in the blood and decrease in nutrients from the blood.

 

[Green Yoda]

Identify some responses of plants to temperature change. (4 marks)

 

[pikachu975]

Identify some responses of plants to temperature change. (4 marks)

Phototaxis
One response to temperature change is the use of phototaxis, where plants bend their leaves according to where the sun is shining from. This is used to either gain more sunlight absorption due to increased surface area being exposed, or to minimise the sunlight being received.

Smaller Leaves
Smaller leaves is a response by plants so that they have less surface area exposed to sunlight, this means that they absorb less of it. The effect of this is that less water is lost through the stomates, increasing water conservation.

Eucalypt
The Australian Eucalypt is an example of a plant that survives Australia's harsh arid conditions. This is through hanging its leaves vertically, so that during midday when the sun is at its hottest, the leaves are not that exposed, increasing water conservation. The leaves are mainly exposed during sunrise and sunset, when the sun is at its coolest, compared to midday. Furthermore, some Eucalypts even close their stomates during the extremely hot and dry temperatures so that transpiration does not occur, because very hot temperatures rapidly increases the rate of water loss.

 

[Green Yoda]

Discuss two ways in which plants can respond to an increase in temperature. (4 marks)

 

[pikachu975]

2009 HSC Q23

A woman recently conceived Britain’s first baby guaranteed to be free
from hereditary breast cancer. Doctors screened for an embryo that was
free from a gene that can cause breast cancer.
The screening was performed due to the long history of this form of
cancer in the family and the fact that any daughter born with the gene
would have a 50%–80% chance of developing breast cancer.

Explain the possible impact of this reproductive technology on the genetic
composition of the population. (2 marks)


The answers just say "This reproductive technology" wouldn't you need to specify the technology? What's the reproductive technology here anyway...

 

[Mathew587]

2009 HSC Q23

A woman recently conceived Britain’s first baby guaranteed to be free
from hereditary breast cancer. Doctors screened for an embryo that was
free from a gene that can cause breast cancer.
The screening was performed due to the long history of this form of
cancer in the family and the fact that any daughter born with the gene
would have a 50%–80% chance of developing breast cancer.

Explain the possible impact of this reproductive technology on the genetic
composition of the population. (2 marks)


The answers just say "This reproductive technology" wouldn't you need to specify the technology? What's the reproductive technology here anyway...

Well I'm pretty sure it's genetic screening. My answer would probs go like this:

Genetic screening refers to the screening on embryonic DNA and can assist in identifying deformities and issues before birth. As a result, the parents can choose whether to continue the birth or to abort. This would result in less genetic variation leading to a more homogenous population but may also result in the deformity being eradicated from the population.

 

[ShootingDuck]

Looking at the marking guidelines, it says nothing about stating the technology;

"Correctly relates widespread use of the reproductive technology to
changes in the genetic composition of the population."

So based on this and the wording of the question you're not expected to know the technology, just it's effects on the genetic composition of the population.

 

[pikachu975]

Looking at the marking guidelines, it says nothing about stating the technology;

"Correctly relates widespread use of the reproductive technology to
changes in the genetic composition of the population."

So based on this and the wording of the question you're not expected to know the technology, just it's effects on the genetic composition of the population.

Yeah but say you were in the exam, you'd probably think you had to name one, that's what I (and others) thought initially

 

[ShootingDuck]

Yeah but say you were in the exam, you'd probably think you had to name one, that's what I (and others) thought initially

That's understandable, i just looked at the marking guidelines to make sure I wasn't giving out the wrong information or if there was indeed a technology like that in the syllabus we're meant to know.

If you guys don't mind checking, would this be an acceptable answer?

"It would decrease the genetic variation in the population since embryos without specific genes are being chosen. This can lead to a decrease in inherited diseases as the genes associated with particular inherited diseases aren’t selected and removed from the population."

Thank you in advance.

 

[pikachu975]

That's understandable, i just looked at the marking guidelines to make sure I wasn't giving out the wrong information or if there was indeed a technology like that in the syllabus we're meant to know.

If you guys don't mind checking, would this be an acceptable answer?

"It would decrease the genetic variation in the population since embryos without specific genes are being chosen. This can lead to a decrease in inherited diseases as the genes associated with particular inherited diseases aren’t selected and removed from the population."

Thank you in advance.

Looks good but maybe instead of saying "It" use "The reproductive technology" because one question in my exam the question said "Julie" and the teacher said he nearly took a mark off people for not putting her name in the answer. Also you could be specific and say "inherited diseases e.g. breast cancer" just to relate to the stimulus.

 

[pikachu975]

http://prntscr.com/gminxd

What would we write for b? Also isn't it a dodgy question since not everyone would study 'wilting' as their plant adaptations...

 

[pikachu975]

http://prntscr.com/gminxd

What would we write for b? Also isn't it a dodgy question since not everyone would study 'wilting' as their plant adaptations...

 

[Mathew587]

You talk about how the xylem carries waters and ions. So if they are thinner, more water and ions will ooze out i.e. through transpiration. This will result in less water and ions being passed to the leaves and the plant itself, resulting in the plant wilting. )

 

[pikachu975]

You talk about how the xylem carries waters and ions. So if they are thinner, more water and ions will ooze out i.e. through transpiration. This will result in less water and ions being passed to the leaves and the plant itself, resulting in the plant wilting. )

The answers for some reason talked about the xylem collapsing so no water can be transported it's weird

 

[pikachu975]

You talk about how the xylem carries waters and ions. So if they are thinner, more water and ions will ooze out i.e. through transpiration. This will result in less water and ions being passed to the leaves and the plant itself, resulting in the plant wilting. )

The answers for some reason talked about the xylem collapsing so no water can be transported it's weird

 

[Mathew587]

The answers for some reason talked about the xylem collapsing so no water can be transported it's weird

who knows... it's meant to be a sample answer anyways
use the answer criteria instead. pretty sure i'd get 3 marks for that q cos thin walls would def result in increased water loss from transpiration.

 

[pikachu975]

who knows... it's meant to be a sample answer anyways
use the answer criteria instead. pretty sure i'd get 3 marks for that q cos thin walls would def result in increased water loss from transpiration.

Isn't transpiration in the leaves via evaporation

 

[Mathew587]

Isn't transpiration in the leaves via evaporation

i meant the loss of water through the stem
"Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers."
pretty sure that includes the stem

 

[ShootingDuck]

Quarantine measures exist to prevent the spread of disease into Australia

Justify TWO measures that you would expect AQIS (the Australian Quarantine and Inspection Service) to take in response to the recent swine flu outbreak in Mexico and North America (4 marks)

 

[Snowflek]

The answers for some reason talked about the xylem collapsing so no water can be transported it's weird

How does that work? How come if the walls of the Xylem are thinner, they collapse? Also, the transpiration cohesion adhesion theory is when water molecules from the leaves evaporate in which the cohesion force between the molecules will act like a train, dragging the liquid water molecule up from the plants body to the leaves to replace the evaporated water molecule. The adhesion force between the molecule and the wall (i guess) will just allow the water to stay in place without it falling back down to the roots or whatever.