Maintaining a Balance, Blueprint of Life. Flashcards
Which of the following best describes the action of aldosterone on kidney tubules?
A) It increases excretion of sodium into urine and reabsorption of water form urine.
B) It decreases excretion of sodium and decreases reabsorption of water from urine.
C) It increases reabsorption of sodium and increases reabsorption of water from urine.
D) It increases reabsorption of sodium and increases excretion of water into urine.
C
Which scientist carried out sea urchin experiments that led to the chromosomal theory of inheritance? A) Gregor Mendel B) Walter Sutton C) Thomas Morgan D) Theodore Boveri
D
The following method describes a procedure to demonstrate the effect of dissolved carbon dioxide on the pH of water.
1. Determine pH of the same quantity of water to which no gas has been added but containing same amount of Universal Indicator.
2. Fit with cork and delivery tube and run gas produced into a known quantity of water containing Universal Indicator.
3. Add Hydrochloric Acid to calcium carbonate in a test tube to produce carbon dioxide.
4. Determine pH by comparing colour of resulting solution with chart.
5. Repeat Experiment.
What is the correct order of steps to carry out a valid experiment?
A) 1,2,3,4,5
B) 3,2,1,4,5
C) 1,3,2,4,5
D) 3,2,4,1,5
C
Red-green colour-blindness is a relatively common condition that is inherited as a sex-linked recessive trait. A 'normal' woman whose father was red-green colour-blind marries a man with normal vision. What proportion of her sons would you expect to be red-green colour-blind? A) All B) Half C) A quarter D) None
B
Define the term enantiostasis and discuss, giving examples of adaptations, its importance to organisms living in an estuarine environment.
Includes:
- Enantiostasis is the maintenance of metabolic activity in response to changing salinity.
- For example, salt excluders, salt accumulators.
- Adaptations allow for consumption of water required for metabolic activity (photosynthesis).
Compare the structure of arteries, capillaries and veins in relation to their function.
Includes:
- Arteries have thick muscular walls, and are elastic. Allows oxygenated blood to travel from heart to body due to high pressure of blood.
- Capillaries have thin walls, one cell thick, and have a branching structure to allow diffusion of blood to travel around the body.
- Veins have thin muscular walls, are large in structure with one way valves in order to allow low pressure blood to travel back to heart.
Australian terrestrial plants have adaptations that make them suitable for survival in arid climate. Name ONE adaptation of Australian plants and explain how this adaptation assists in the survival of the plants in an arid climate.
Includes:
-The closing of stomates to prevent water loss during arid climates to retain water.
Movement of materials against the concentration gradient is called? A) Diffusion B) Osmosis C) Transpiration D) Active Transport
D
Discuss the potential impact of the use of reproduction technologies on the genetic diversity of species, using a named example of a plant and an animal that have been genetically altered.
Includes:
- Cloning:
* The potential impact is that the genetic diversity of organisms will be decreased.
* Cloning techniques for domestic animals, such as those that produced Dolly, and the genetic modification of livestock for increased size, such as sheep and pigs, could result in multiple identical genetic copies becoming widespread in the populations with a subsequent loss of natural variation.
* Some genetically engineered crops and their modifications are:
- Soy bean- herbicide tolerance.
- Cotton- Insect resistance and herbicide tolerance.
- Papaya- virus resistance to papaya ringspot virus.
( Herbicide tolerance means that farmers can spray greater amounts of herbicides on their land).
Name and describe several types of rearrangement of DNA.
Includes:
- Inversions, translocations, duplications and amplifications are all types of rearrangement of DNA which result in mutations.
• In duplication, an extra copy is made of a sequence on the same chromosome.
• In inversion, a DNA sequence breaks and is then re-attached the wrong way around.
• In translocation, a piece of DNA from one chromosome joins onto another chromosome.
• In amplification, many extra copies of a DNA sequence are found on a chromosome.
• In substitution, one base is replaced by another base.
• In deletion, a base is lost from a chromosome.
• In insertion, an extra base is inserted into the DNA.
Explain how Darwin’s theory of evolution is supported by the genetic information we now have.
Includes:
- Darwin’s theory of evolution by natural selection can be explained and expanded by the genetic information we now have. Variation in a population comes from:
• The random fusion of gametes in sexual reproduction.
- Crossing over of pieces of homologous chromosomes during meiosis.
- Random assortment of chromosome pairs in meiosis.
- Mutations of chromosomes and genes.
Describe how Beadle and Tatum investigated mutations and developed the “one-gene-one-enzyme” hypothesis.
Includes:
- In 1941, George Beadle (1903-89) and Edward Tatum (1909-75) proposed the one gene- one enzyme hypothesis after conducting a series of experiments with the bread mould Neurospora Crassa. Neurospora is a fungus with a haploid genome- only one copy of each gene. They exposed the spores of the fungi to X-rays or UV radiation to produce mutant varieties that had special nutritional needs. For example, one mutant would only grow if the agar plate contained the amino acid arginine. To clearly identify the defect, Beadle and Tatum investigated the three steps in the synthesis of arginine.
- Precursor nutrient –enzyme 1-> ornithine –enzyme 2-> citrulline –enzyme 3-> arginine
- They found three types of mutants for arginine when grown on a minimal medium and the chemical stages which led to arginine synthesis.
Describe what cloning is and explain its different methods.
Includes:
- Cloning is the method of producing genetically identical organisms.
- Asexual reproduction in both plants and animals results in clones, or offspring that are genetically identical to their parent.
- Methods of cloning include:
- Nuclear Transfer; The technique used to clone mammals in this way involves transferring the nucleus from the cell of an adult into an egg cell that has had its nucleus removed. The egg is then implanted in the uterus of a female, where it can grow and develop as a normal embryo.
- Embryo Splitting; A sperm and an egg are artificially combined and the resulting embryo is cultured in the laboratory and allowed to split into two cells, then four, then eight. At the eight-cell stage the embryo is split to produce four genetically identical two cell embryos. These embryos are then transferred to the uterus of a surrogate mother to grow and develop.
- Therapeutic Cloning; Uses genetic engineering techniques to produce lines of cultured stem cells.
Antibodies are proteins that: A) Break down pathogens B) Bind with a specific agent C) Catalyse biochemical reactions D) Are produced by T cells to kill disease carrying viruses
B
Which of the following can cause an imbalance of microflora in humans?
A) Overuse of antibiotics
B) Excessive use of antiviral drugs
C) Consumption of genetically modified food
D) Immunisation against different diseases
A
