Revision sheet genetics answered blog


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Revision sheet genetics answered blog

  1. 1. Genetic website references to overview Natural selection – use you notes and material given in class.1) What is a genotype? Genotype is the combination of alleles (genes) that make up the gene – represented in letters. i.e. LL, Ll (lL), ll /22) What is a phenotype? Phenotype is the physical characteristic of the gene i.e. attached lobe /23) What is mitosis? Mitosis is the process of one cell splitting into 2 cells. /24) What is a chromosome? Where can chromosomes usually be found? A chromosome consists of a long DNA stand tightly coiled over and over itself, forming a chromosome. Chromosomes are usually found inside the nucleus. /25) A karyotype?A Is the number and appearance of B Is the physical appearance of a chromosomes particular geneC Is the result of two dominate genes D A typewriter that is carried on a mixed together camel’s back. /26) How many chromosomes do humans typically have? A 22 B 44 C 23 D 46 /27) What sex chromosomes will a female have? Male? A female will consist of 2 X chromosomes. A male will consist of an X and Y chromosome
  2. 2. 8) How are genes passed on through offspring? Genes are passed on through DNA. ½ from the mother and ½ from the father /29) What is the difference between incomplete dominance and co-dominance conditions?Incomplete dominance is a blend of both inherited genes, whilst co-dominance will show bothinherited genes that is not a blend.(Incomplete dominance is a condition when neither allele inherited is dominant or recessive overthe other. i.e. A red and a white flower will produce a pink flowerCo-Dominance is when both alleles contribute to the phenotype of an organism. I.e. a black and awhite chicken’s offspring will produce a white and black spotted/speckled chicken.) /2Far away on another planet a purple cat mated with a red cat and was due to have 8 kittens. Uponexamining the genetic makeup and breeding history of the cats, the colour allele was determined; Purple allele are dominate, Red allele are recessive.10) Figure out the ratios of the possible off springs genotypes and phenotypesNote: as red is recessive, its genotype will be rr (r representing red – lower case as its recessive).As Purple is a dominant allele the genotype of a purple cat can be PP or Pr (P representing purple– capital as it represents dominant). P P P r r Pr Pr r Pr rr r Pr Pr r Pr rrRatio of offspring if the purple cat is Pr – 1:1, genotype Pr : rr, phenotype purple : red respectivelyRatio of offspring if Purple cat is PP- All cats will be purple and have a genotype of Pr11) Is it possible for all offspring to be purple? Why or why not?Yes only is the purple cats genotype is PP, a purebred. As the red cat will have a genotype of rr,when mating the offspring will receive one gene from each parent hence all off spring will be Pr. AsP (purple) is dominate all offspring will be purple.
  3. 3. 12) Complete the table below Human Blood Types Phenotype Genotype A AA or Ao B BB or Bo AB AB o oo13) Write a description regarding natural selectionIndividuals with favourable characteristics for the environment are said to be betteradapted to the environment. Individuals with unfavourable characteristics for theenvironment will usually die off/before they are able to reproduce /214) Give a brief scenario where mutation for a living object is an advantage and anotherscenario where it is a disadvantage?A mouse mutates and has razor sharp poison spikes that can spring up along its back.This would be an advantage, as it serves as a defensive mechanism when birds capturemice causing the bird to release to mouse and it has a higher chance to survive. A Mouse living in a rainforest mutates and 3 legs causing it to move slower. This would bea disadvantage as it will not be able to flee or out manoeuvre its prey. /215) Two colour types of frogs exist in the world Millions of years ago. One type Green and the other Earth in colour. Which frog would be more likely to be found in the outback? Why? Which frog would exist in the forest? Why? If all the forests died which frog would survive? Why?The earth colour frog would more likely be found in the outback as its colour would blendinto its environment giving it a higher chance of survival and reproducing.The green colour frog would be more probable to exist in the forest due to its colourblending into its environment. However the earth colour may exist in there to.The earth colour frog would most likely survive if all the forests died as its colour will help itblend into the environment. However would anything exist without trees and forests?