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Unit 2 Biology
| Question | Answer |
|---|---|
| Define: gene | a section of DNA that carries the code to make a protein |
| Define: allele | alternative forms of a gene |
| Define: genome | the complete set of DNA contained within an organism's chromosomes |
| Define: locus | the fixed position on a chromosome where a particular gene is located |
| Define: chromatid | one half of a replicated chromosome |
| What is a chromosome? | the structure made of protein and nucleic acid that carries genetic information |
| What are homologous chromosomes? | a pair of chromosomes of similar length, gene position and centromere location. one pair is inherited from the mother and the other from the father. |
| What is a karyotype? | a visual representation of an individual's entire genome organised into homologous pairs |
| How many chromosomes does a normal human have? | 46 chromosomes |
| What is aneuploidy? | when a cell or organism varies in the usual number of chromosomes in it's genome by the addition or loss of a chromosome |
| What is polyploidy? | when an organism contains additional sets of chromosomes in its genome |
| Why is meiosis a necessary process in many living organisms? | it is important for sexual reproduction and creates genetic diversity in the population |
| What cells are produced by meiosis? | 4 gamete cells (sex chromosomes) |
| What are haploid cells? | describes a single set of chromosomes (n) |
| What are diploid cells? | cells or organisms that have two sets of chromosomes (2n) |
| Explain crossing over in relation to meiosis | the exchange of genetic material between non-sister chromatids during prophase I of meiosis, resulting in new combinations of alleles in daughter cells |
| Outline the stages of meiosis | Interphase Prophase I Metaphase I Anaphase I Telophase I Prophase II Metaphase II Anaphase II Telophase II Cytokinesis |
| Define: homozygous | having identical alleles for the same gene on homologous chromosomes |
| Define: heterozygous | having different alleles for the same gene on a homologous chromosome |
| What is co-dominance? | a pattern of dominance where both alleles from the genotype of a heterozygous individual are dominant and expressed in the phenotype of that organism |
| What is incomplete dominance? | a pattern of dominance where neither allele from the genotype of a heterozygous individual is dominant and both are expressed in an intermediate phenotype |
| What are sex linked genes? How are they written? | genes that are located on a sex chromosome. Females are written as XX and males are XY |
| What is epigenetics? How does it work and what is it's importance? | changes to an organism's phenotype resulting from modifications to gene expression. |
| Define: mutualism | interactions between two organisms of different species where both parties experience some overall benefit |
| Define: commensalism | interactions between two organisms of different species where one gains some benefit while the other experiences no significant benefit or harm |
| Define: ammensalism | interactions between two species where one organism experiences some negative effect while the other experiences neither a beneficial nor negative effect |
| Define: competition | interactions between two or more organisms competing for the same pool of resources |
| Define: Parasite/ Host | interactions between two organisms of different species where one organism obtains nutrients at the expense of a host organism |
| Define: Predation | interactions between different species where one organism hunts and kills another for food |
| How does epigentics work? | Epigenetics works through transcription and translation. |
| what is epigentics importance? | It's importance is to help control cell differentiation, providing a mechanism for a developing organism to respond to its environment |
| Explain independent assortment in relation to meiosis | the random orientation of homologous chromosomes along the metaphase plate during metaphase I. |
| What is a keystone species? | a species whose effects on an ecosystem are greater then expected relative to its population size |
| What is asexual reproduction? | producing offspring without the fusion of gametes |
| What is cloning? | is a genetically identical organism or section of DNA |
| Advantages for asexual reproduction | asexually reproducing population grow faster than sexually reproducing populations, offspring are identical clones of the parents |
| Disadvantages for asexual reproduction | genetic diversity is low and asexually reproducing populations may suffer during rapid environmental change |
| What is sexual reproduction? | is the fusion of two distinct haploid gametes to produce a single diploid zygote composed of two sets of chromosomes |
| Advantages for sexual reproduction | increases genetic diversity of a population by allowing for recombinant offspring, improving disease resistance by promoting the presence of different alleles |
| Disadvantages for sexual reproduction | the cost of male progeny, the time, energy and resources it takes to attract and find a mate, the risk of transferable diseases associated with sexual intercourse |
| What is a Somatic cell transfer? | is the transference of a somatic cell nucleus into an enucleated egg cell |
| How was Dolly the sheep produced? | A number of embryos were produced from a Finn Dorset ewe and a Scottish blackface ewe. Eventually one gave birth to a healthy Finn Dorset lamb- Dolly. |
| What is a test cross? | when an individual expressing the dominant phenotype but with an unknown genotype is crossed with a homozygous recessive individual. the results will show whether the individual is homozygous dominant or heterozygous |
| When is a test cross used? | it is used when an individual is expressing the dominant phenotype but has an unknown genotype |
| Adaptations for hot environments | structural- less insulation, low SA:V ratio behavioural- evading extreme conditions, enduring extreme conditions physiological- surface blood flow, increase water input, metabolic heat, decrease water output, evaporative cooling |
| Adaptations for cold environments | structural- insulation, low SA:V ratio behavioural- huddling, seeking shelter, migrating to a warmer climate physiological- torpor, circulation |
| Which cells in SCNT are diploid and/or haploid? | the enucleated cell contains no sets of chromosomes whereas the somatic cell has a full set of diploid chromosomes and therefore when put together they create a diploid somatic cell. |
Created by:
emma.hill
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