non-disjunction is a pathological event that occurs during the second anaphase in meiosis when sister chromatids are not separated. As a result one of the resulting cells will have 1 extra chromosome and the other will be 1 short. An example of a non-disjunction that can occur in humans is Down syndrome that has a frequency of about 1/1000 people. It is caused by the non-disjunction of the 21st pair of chromosomes.
During glacial maxima, Australia, new guinea, and Tasmania were a single land mass called Sahul.
- The single Pleistocene continent known as Sahul united Australia with New Guinea and Tasmania. Rising sea levels gave rise to the distinct landmasses that we can now recognize, even though the sea level at the time was up to 150 meters (490 feet) lower than it is now.
- Australia, New Guinea, Tasmania, and Seram were all parts of the ancient continent Sahul.
- Since the Last Glacial Maximum, sea levels have risen. Around 18,000 years ago, Sahul began to be partially submerged. Sea levels kept rising until roughly 5000 BCE.
- After leaving Africa, early human migrations began in Sahul and Sunda. According to recent study, hundreds of individuals traveled in groups on bamboo rafts and eventually settled on Sahul.
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Answer:
The nucleus at the central part of the cheek cell contains DNA. When a drop of methylene blue is introduced, the nucleus is stained, which makes it stand out and be clearly seen under the microscope.
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Answer:
a) The genes present on separate chromosomes exhibit indepedent assortment.
b) The genotype of tall and purple flower parent= TTPp
The genotype of short and purple flower parent: ttPp
Explanation:
a) In a dihybrid cross, if the genes are present on the same chromosome, they will not exhibit independent assortment. The genes present on the same chromosome are called linked genes. Linked genes are inherited together. The absence of independent assortment of a linked gene gives more of parental types in F2 progeny. Therefore, if genes are not present on a separate chromosome, Mendel’s ratios deviate.
b) Alleles for tallness and purple flower are dominant. In the progeny, all the plants are tall. This means that the dominant tall plant is homozygous. With respect to flower color, the trait exhibits segregation of dominant and recessive alleles and both purple and white flower progeny are obtained. This makes both the plants heterozygous for the flower color gene.
The genotype of tall and purple flower parent= TTPp
The genotype of short and purple flower parent: ttPp
Answer:
5%
Explanation:
Frequency of white tigers = 4%
population of tigers = 200
number of heterozygotes = 10
<u>Determine the actual genotype frequency of Heterozygotes </u>
frequency of heterozygotes = Number of heterozygotes / population
= ( 10 / 200 ) * 100
= 0.05 * 100 = 5%
