Biology 2013ers MARATHONN (1 Viewer)

[Spiritual Being]

shoulda done comm. aligns better. wooooooooooo

I'll do both. The better questions, I'll do.

 

[obliviousninja]

I'll do both. The better questions, I'll do.

pls tell me ur kiddin

 

[obliviousninja]

just like me. studied hamlet, didn't like question, did speeches

 

[yasminee96]

Public health programs, pesticides and genetic engineering are used to control and/or
prevent disease.
Using an example, explain how ONE of these strategies has been used to control
or prevent disease within the community.

Genetic Engineering is the process that involves altering genetic composition of an organism in some way. By altering genetic make-up of organisms, it is possible to make them resistant to some diseases, thus preventing them from occuring. Many Agricultural crops have been genetically modified with the insertion of Bt, allowing the plants to produce a natural insecticide, killing insect pests that feed on plant tissue. Cotton plants have been genetically modified in this way (known as Bt cotton), so that they can protect themselves from attacks of insects that feed on them. This is advantageous as it reduces the impact on the surrounding environment (in comparison to normal insecticides/pesticides). Also, many patients who suffer from diseases such as diabetes have had their genes modified by the insertion of the gene coding for the protein that produces insulin into their genes, allowing the production of insulin. In doing so, it has controlled the disease of diabetes in the wider community. Thus, overall, genetic engineering has been proven useful to control specific diseases, and prevent the spread of disease.

Do correct if i'm incorrect

Define the term enantiostasis and outline the methods used by estuarine plants to maintain appropriate internal salt concentrations. (not sure if this has already been asked)

 

[Sy123]

 

[yasminee96]

(a) Coagulation and Disinfection
(b) Coagulation occurs when chemicals are added to the untreated water supply, which allow dirt, plant debris and other organic matter to clump together. These clumps are known as "floc", which settle to the bottom, and thus are removed. In removing these flocs, pathogens that exist in the organic matter are thus removed from the water supply, reducing the risk of pathogens reaching consumers, and thus reducing risk of infection.
After Coagulation, sedimentation and filtration are completed, microorganisms such as E. Coli, Cryptosporidium and Giardia may still exist in the water from animal carcasses and faecal supply. These microorganisms can cause infection in the intestines of humans. Disinfectants such as chlorine are added to the water to kill disease-causing pathogens such as giardia, and remains in the water as it travels through pipes to consumers, further reducing the risk of pathogens in the water. In doing so, risk of infection via pathogens existing in water are reduced tremendously.

My answer seems too long though...


Explain the relationship between replication of DNA and evolution. /5 (HSC 2012 question)

 

[Menomaths]

Genetic Engineering is the process that involves altering genetic composition of an organism in some way. By altering genetic make-up of organisms, it is possible to make them resistant to some diseases, thus preventing them from occuring. Many Agricultural crops have been genetically modified with the insertion of Bt, allowing the plants to produce a natural insecticide, killing insect pests that feed on plant tissue. Cotton plants have been genetically modified in this way (known as Bt cotton), so that they can protect themselves from attacks of insects that feed on them. This is advantageous as it reduces the impact on the surrounding environment (in comparison to normal insecticides/pesticides). Also, many patients who suffer from diseases such as diabetes have had their genes modified by the insertion of the gene coding for the protein that produces insulin into their genes, allowing the production of insulin. In doing so, it has controlled the disease of diabetes in the wider community. Thus, overall, genetic engineering has been proven useful to control specific diseases, and prevent the spread of disease.

Do correct if i'm incorrect

Define the term enantiostasis and outline the methods used by estuarine plants to maintain appropriate internal salt concentrations. (not sure if this has already been asked)

Enanstiostasis is the maintenance of internal functions in response to variations in the environment.
Estuarine plants need ways to cope with the changing salinity levels of an estuary, where freshwater mixes with saltwater. Some adaptations which enable these plants to cope with the fluctuating conditions are;
salt prevention: The movement of salt is not allowed into the xylem vessels of the plants
salt accumulation: Where salt is stored in leaves and dropped off later
Don't know mark value so I'll leave it there

 

[yasminee96]

Enanstiostasis is the maintenance of internal functions in response to variations in the environment.
Estuarine plants need ways to cope with the changing salinity levels of an estuary, where freshwater mixes with saltwater. Some adaptations which enable these plants to cope with the fluctuating conditions are;
salt prevention: The movement of salt is not allowed into the xylem vessels of the plants
salt accumulation: Where salt is stored in leaves and dropped off later
Don't know mark value so I'll leave it there

My bad, was a 3 marker - one for defining enantiostasis and 2 for second part.
Try and memorise the definition from the syllabus though! "maintenance of metabolic and physiological functions in response to variations in the environment"
and I think you would need specific plant examples as well. This was a 2003 hsc question, and the markers' comments had something about people's examples :/ I personally only have animal examples. Anyone have any plant examples?

 

[Menomaths]

My bad, was a 3 marker - one for defining enantiostasis and 2 for second part.
Try and memorise the definition from the syllabus though! "maintenance of metabolic and physiological functions in response to variations in the environment"
and I think you would need specific plant examples as well. This was a 2003 hsc question, and the markers' comments had something about people's examples :/ I personally only have animal examples. Anyone have any plant examples?

This is for the Grey Mangroves iirc

 

[yasminee96]

This is for the Grey Mangroves iirc

ah yes, thank you!

Try answering my other question?

 

[Menomaths]

ah yes, thank you!

Try answering my other question?

Did it before

Even Sy asked that question lol

 

[Candidate]

From the '04 HSC:

Justify continued research into the development of artificial blood (3)

 

[Menomaths]

From the '04 HSC:

Justify continued research into the development of artificial blood (3)

Continued research into the development of artifical blood is required because there are a number of problems associated with donated blood, such as;
1)There is a shortage of donated blood
2)Short shelf-life
3)Has to be cross-matched, if wrong blood type is given it can be fatal, disadvantageous in emergency situations
4)Needs to be sterile, free of diseases etc
Thus, research is needed to develop artificial blood which can overcome these problems.
(I don't know if we have to talk about this, but I'll do it anyway)
Perfluorocarbons have been developed to combat these problems and have been successful in doing so, as they:
1)Are synthetic inert and sterile
2)Can dissolve more oxygen than blood
3)Have a long shelf-life
4)Don't need to be cross-matched
But they must be emulsified before being injecting into the bloodstream.

 

[Menomaths]

1)Describe two mechanisms that allow the interaction between B and T lymphocytes.

2)Describe how gene expression is linked with maintenance and repair of body tissues.

 

[yasminee96]

1)Describe two mechanisms that allow the interaction between B and T lymphocytes.

Secretion of Chemicals: interleukin secreted from Helper T cells which activate B cells and Cytotoxic T cells
MHC molecules/Surface molecules of macrophages and B cells display the antigen for recognition by the helper T cells.

2)Describe how gene expression is linked with maintenance and repair of body tissues.

When mutations occur on genes that code for proteins, essentially their gene expression does not occur normally. This may then lead to a disruption and lack of control of the cell cycle, a lack of control of the genetic stability, and affects mitosis. When mitosis is negatively affected, it leads to problems in the maintenance of and repair of body tissues. This is illustrated clearly with the example of Breast Cancer. A mutation may occur in the BRCA1 gene, a gene associated with coding for proteins that repair the PTEN gene, a tumor suppressor cell that limits cell divisions and encourages cell death (for genetic stability). Thus, if the BRCA1 gene is not expressed correctly, then the PTEN gene cannot be repaired by the BRCA1 gene, leading to a lack of control of the cell cycle and cell divisions which eventually lead to cancer on the breast. Hence, the way gene expression is linked with the maintenance and repair of body tissues is that if gene expression is not carried out correctly, maintenance and repair of body tissues will not occur correctly either.

 

[ocatal]

1) B and T lymphocyte interactions are initially enabled by the chemical cytokine secretions of interleukin-2 which results in the extensive cloning of B and T cells. This allows for complex interactions between the two lymphocytes, further aided by their close proximity to each other. In addition, the integration of the MHC system allows for cell identification as either 'foreign' or 'self,' further contributing to the interactions between B and T cells.

Identify and describe the processes used by various plants for salt regulation in highly saline environments.

 

[superSAIyan2]

Exclusion: E.g grey mangroves have an ultrafiltration system in their roots to actively exclude Na+ uptake
Accumulation: Salt ions are actively transported away from sensitive cells and to specialised salt glands where they accumulate to reduce toxic effects on plant tissue. these are shed or burst open to release salt when their storage capacity is exceeded (e.g. Milky Mangrove)
Secretion: Plant leaves may actively secrete salts to maintain an optimal osmotic pressure in their cells
Dilution: Some plants may increase water intake to dilute salts, thus reducing their toxic effects on cells

Antibiotics have played a significantly beneficial role in 20th Century medicine. Evaluate their impact on current medical practice and modern society. 5M

 

[fionarykim]

1) B and T lymphocyte interactions are initially enabled by the chemical cytokine secretions of interleukin-2 which results in the extensive cloning of B and T cells. This allows for complex interactions between the two lymphocytes, further aided by their close proximity to each other. In addition, the integration of the MHC system allows for cell identification as either 'foreign' or 'self,' further contributing to the interactions between B and T cells.

Identify and describe the processes used by various plants for salt regulation in highly saline environments.

Mangroves - have root barriers in which they prevent the entry of salt into their roots in the first place
-are able to store salt in their leaves, and when the salt concentrations become too high, they can be excreted
Salt bush - have special salt glands in which the salt are accumulated, then these glands can be dropped to remove the salt

Explain how the processes of filtration and reabsorption in the mammalian nephron can account for the changes in concentration of the sodium ions, glucose and urea

 

[fionarykim]

Looks like we'll need to start this up again before exam.

Filtration in the mammalian nephron involves passive transport of nutrients in blood such as glucose, salts and urea that are pushed to Bowman's capsule through high blood pressure, hence responsible for change in concentration of these materials in the body?

Reabsorption in the mammalian nephron occurs in the proximal to the distal tubules that can actively absorb salt into the capillaries. I'm confused about the changes of these concentrations, in terms of where? blood? filtrate or body?

Q) Sutton, Boveri and Morgan worked in the field of genetics. Describe the contribution made by two of these scientists to the understanding of chromosomal nature of inheritance? 4 Marks (2001-2003 HSC)

Boveri- worked with sea urchins and discovered that 50% of chromsomes were from father, and the other 50 was from the mother. Suggested that there was alink between chromosmes and inheritance, also demonstrated that a full set of chromosomes was required for normal development. (both boveri and sutton independently) came up with the chromosomal theory of inheritance
Morgan- worked with fruit flies in which he crossed white eyed fruit flies with red eyed, first generation was all red as expected, however second generation did not give 3:1 mendlian ratio as expected. Also realised that all of the white eyed flies were male. At first thought that it would be a characteristic only possible for males, but he eventualy could produce a female with white eyed. Suggested that the chromosome for white eyes was on the sex chromosome and hence came up with linkage. This allowed us to understand that genes could also be located on sex chromosome and hence enhanced our understanding of inheritance.

slightly less mainstream Qs
outline the historica development of theories of evolution and assess the extent of social and political influences on these theories


James Watson, Francis Crick, Rosalind Franklins and Maurice Wilkins contributed to
discovery of the structure of DNA.
Evaluate the impact of this discovery on current genetic technology.

 

[bangladesh]

slightly less mainstream Q
outline the historica development of theories of evolution and assess the extent of social and political influences on these theories

How many marks?