Term
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Definition
| a heritable factor that controls a specific characteristic |
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Term
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Definition
| one specific form of a gene |
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Term
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Definition
| the complete set of an organism's base sequence |
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Term
| Explain the consequences of a base substitution using sickle cell anemia as an example. |
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Definition
mutation is a change in DNA sequence;
changes the mRNA during transcription;
changes the amino acid sequence;
substitution mutation / changes to one codon;
glutamic acid is changed to valine / GAG to GTG;
changes the shape of hemoglobin /
hemoglobin becomes less soluble and crystallizes out;
cannot carry oxygen as well;
red blood cells sickle / impairs blood flow;
causes other health problems / anemia / tiredness, shortness of breath;
sickle cell anemia caused by two mutated recessive alleles; |
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Term
| Describe, with the aid of a diagram, the behaviour of chromosomes in the different phases of meiosis. |
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Definition
chromosomes condense / coil /
become shorter and fatter during prophase I;
(homologous) chromosomes pair up in prophase I;
crossing over / chiasmata formation in prophase I;
movement of pairs of chromosomes /
bivalents to the equator in metaphase I;
movement of half of the chromosomes to each pole in anaphase I;
movement of chromatids to opposite poles in anaphase II;
decondensation / uncoiling in telophase II;
(if no diagram, you will lose 1 mark) |
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Term
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Definition
| Two chromosomes with the same set of genes, in the same sequence, sometimes with different alleles |
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Term
| What are the final products when a diploid onion cell, containing 16 chromosomes undergoes meiosis? |
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Definition
| 4 haploid cells containing 8 chromosomes each |
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Term
| Explain what causes down's syndrome? (be able to identify from karyotype) |
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Definition
| non-disjunction, which is where 2 or more homologous chromosomes stick together instead of separating. In Down's Syndrome, non-disjunction occurs on the chromosome 21, resulting in a trisomy rather than a pair. |
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Term
| A tiny amount of DNA was obtained from a crime scene and amplified. Following digestion with restriction enzymes, which laboratory technique would be used to separate the fragments of DNA? |
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Definition
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Term
| If a man has blood group O and a woman has blood group AB, what is the probability that their child will be blood group O? |
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Definition
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Term
Which processes result in the greatest amount of genetic variation in a population?
A. Natural selection and meiosis
B. Meiosis and mutation
C. Mutation and mitosis
D. Mitosis and natural selection |
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Definition
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Term
| Why is it possible for a gene from one organism to be introduced and function in a different organism? |
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Definition
| The genetic code is universal. |
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Term
Which human trait shows a pattern of polygenic inheritance?
A. ABO blood type
B. Sickle cell anemia
C. Skin colour
D. Co-dominant alleles |
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Definition
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Term
What are the functions of the polymerase chain reaction (PCR)?
I. Copy fragments of DNA
II. Amplify fragments of DNA
III. Translate fragments of DNA
A. I and II only
B. I and III only
C. II and III only
D. I, II and III |
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Definition
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Term
| What is the relationship between Mendel’s law of segregation and meiosis? |
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Definition
| Only one of a pair of alleles appears in a gamete. |
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Term
| What is the relationship between Mendel’s law of segregation and meiosis? |
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Definition
| Only one of a pair of alleles appears in a gamete. |
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Term
Hemophilia is sex-linked and is caused by a recessive allele. A woman’s father has hemophilia, but her husband does not.
What is the probability of the women and her husband having a child with hemophilia? |
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Definition
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Term
Mendel crossed pure breeding (homozygous) tall pea plants that had coloured flowers with pure breeding dwarf pea plants that had white flowers. All of the resulting F1 plants were tall and had coloured flowers.
If Mendel had crossed these F1 plants with a pure breeding strain of dwarf pea plants with coloured flowers, what proportion of tall coloured plants would be expected in the offspring? |
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Definition
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Term
| If a purple flowered (Pp) and a white flowered pea plant (pp) are crossed, what will the offspring be? |
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Definition
| 1 : 1 ratio of purple and white flowers |
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Term
| What does a karyotype show? |
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Definition
| The number and appearance of chromosomes |
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Term
Which processes always occur in meiosis but not normally in mitosis?
I. Chiasmata formation
II. Recombination of genes
III. Separation of homologous chromosomes
A. I and II only
B. II and III only
C. I and III only
D. I, II and III |
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Definition
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Term
Which event occurs first in meiosis?
A. Centromere appearance
B. Chiasmata formation
C. Crossing over
D. Synapsis |
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Definition
A. Centromere appearance
OR
D. Synapsis
(both acceptable) |
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Term
| Which features of DNA fragments are used to separate them in the process of gel electrophoresis? |
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Definition
| A. Their charge and their size |
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Term
| Define the terms gene and allele and explain how they differ. |
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Definition
gene is a heritable factor / unit of inheritance;
gene is composed of DNA;
gene controls a specific characteristic /
codes for a polypeptide / protein;
allele is a form of a gene;
alleles of a gene occupy the same gene locus / same position on chromosome;
alleles differ (from each other) by one /
a small number of base(s) / base pair(s); |
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Term
| Explain how meiosis results in great genetic variety among gametes. |
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Definition
homologous chromosomes form tetrads / bivalents / pairs / undergo synapsis;
crossing over;
during prophase I;
exchange of DNA / genes / alleles between (non-sister) chromatids / chromosomes;
description / diagram of chiasma;
new combinations of maternal and paternal genes / alleles / DNA;
bivalents / homologous chromosomes orient / align themselves on equator randomly;
during metaphase I;
orientation of one homologous pair of chromosomes is independent of others;
homologous chromosomes separate / move to opposite poles;
independent assortment(of unlinked genes);
leads to 2n / 223 possible gametes (without crossing over);
additional variation when chromatids separate in second division; |
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Term
| Discuss the ethical issues for and against the use of transgenic plants. |
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Definition
Responses must have at least two arguments for and two arguments against
to receive full marks.
arguments for:
transgenic plants do not survive long in wild;
reduced cost of food production / reduce amount of land used for food production;
transfer of genes occurs naturally;
DNA and proteins are digested (unlikely to cause problems);
longer shelf life for certain products;
increased yield / bred for faster growth;
better adaptation to certain conditions / eliminate possible plagues;
healthier food produced because use of pesticides can be decreased eg Bt corn /
increase food quality eg albumin gene has increased sulfur amino acid content of
alfalfa used to feed sheep;
arguments against:
uncertain long-term health effects from eating transgenic crops / may contain
animal genes;
new proteins in food crops could cause allergies;
genes could escape from transgenics to wild plants;
create superweeds / damage ecosystems;
monopoly (created by large companies) adversely affects small farmers; |
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Term
| Explain Mendel's Law of Independent Assortment, |
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Definition
| Mendel's Law of Independent Assortment states that "Allele pairs separate independently of each other during the formation of gametes." |
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Term
| In a cross between red haired cattle and white haired cattle the offspring produced are always a color called roan (light reda). If the roan cattle are interbred they produce white, roan, and red offspring. How many alleles are controlling this character? |
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Definition
| Two alleles (CODOMINANCE) |
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Term
| What is a difference between autosomes and sex chromosomes? |
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Definition
| Sex chromosomes determine gender and autosomes do not. |
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Term
| Explain how crossing over in prophase I (between non-sister chromatids of a homologous pair) can result in an exchange of alleles. |
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Definition
The homologous pairs are held together during prophase I.
The position at which the exchange occurs is called the chiasma. The recombinants will form between non-sister chromatids which are crossing over. The homologous pairs remain attached at the chiasma until anaphase I when they are pulled apart. After anaphase II, the chromatids are separated. |
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Term
| What are the recombinants of GGLL and ggll if these traits are linked? |
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Definition
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Term
| Outline two examples of transgenic techniques in agriculture. One example must be in plants and the other in animals. Include the example, the specific method/genes that allows this to occur and the effect on the plant or animal. |
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Definition
PLANT:transgenic sheep to get protein called factor IX which is needed by people with haemophilia to help clot blood. protein is in their milk.
ANIMAL: proteins used by fish to resist the icy temperatures of arctic waters are now produced by the modified tomatoes to make them more resistant to cold |
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