Answer:
The mechanism that Darwin proposed for evolution is natural selection. Because resources are limited in nature, organisms with heritable traits that favor survival and reproduction will tend to leave more offspring than their peers, causing the traits to increase in frequency over generations.
The reason that natural selection is important is that it's the central idea, stemming from Charles Darwin and Alfred Russel Wallace, that explains design in nature. It is the one process that is responsible for the evolution of adaptations of organisms to their environment.
Explanation:
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Answer No 1:
The set up of the punnet square is shown in the attached diagram. As the alleles assort independently hence the gametes formed will be OT,Ot,OT,Ot and OT,Ot,oT,ot. These will be the outcomes of the possible gametes formed. When these gametes are cross bred, the results are shown in the diagram attached.
Answer No 2:
The outcomes of each possible genotype are:
OOTT = 2/16
OOTt = 4/16
OOtt = 2/16
Oott = 2/16
OoTT = 2/16
OoTt = 4/16
Answer No 3:
The likelihood of each possible offspring phenotype is:
Orange petals with tall stem and orange petals with small stems present in ratio 12:4 i.e. 3:1.
Answer:
The fewer number of T cells a person has, the more chances to be affected by an opportunistic infection. When the number of T cells reaches 200 cells/µl, the person is at risk of being infected by other infections.
Explanation:
The whole immune system of a person who is infected with HIV infection seems to be severely affected. When the person is not treated or the disease is in a very advanced stage, the depletion of the T- cells turns to be very sharped, especially CD4+ T cells. At this point, the immune system can not resist the attack of other microorganisms. The <em>lower is the number of CD4+ T Cells, the higher possibility the person has to be attacked by opportunistic infections. </em>
Classically, it has been suggested that opportunistic infections appear after the CD4 + T lymphocytes reach very low levels, such as 200 cells/µl. The number of circulating T cells can be used as an indicator and a measure of global "immune competence", and the previously mentioned amount of CD4 + T cells is an accepted universal reference used to predict the risk of having one of these opportunistic infections.
The different number of maternal and paternal chromosomes possible will be 8. that is option A is correct.
Chromosomes are defined as the genetic material within the body. They are thread like structures within the DNA and are made of proteins. In general human body has 23 pairs of chromosomes out of which 22 are numbered while 1 is the sex chromosome. Gametes are genetic material that are generally haploid in nature and they carry only one chromosome along with them. According to the question, there are 6 diploid chromosomes present which means there are 3 pairs of chromosomes. So each gametes will have a total number of 3 chromosomal pairs irrespective of their type that is maternal or paternal. Therefore combination of maternal and paternal chromosomes are given by
Combination = 2ⁿ where n is pair of chromosomes and here n = 3
Combination = 2³ = 8
Learn more about chromosomes at:
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Complete Question :
If an organism has a diploid number of 6 chromosomes, how many different combinations of maternal and paternal chromosomes are possible in its gametes?
A. 8
B. 12
C. 3
D. 16
E. 6