Answer:
The biomes that experience very hicg seasonal variation in temperatures are Desert and temperate grassland.
Explanation:
Temperate grassland are characterized by seasonal temperature variations. They have pronounced annual fluctuations in temperature with hot summers and cold winters. In the case of deserts, they have huge differences in temperature between summer and winter, and moreover, between the same day and night, which can vary over 40°C.
The answer for this question is b
Genetic variation is caused by mutations in the gametes and meiosis.
The large ears of the rabbits may help them hear when predators are coming. If they hear them coming, then they may be able to escape.
A polar bear with dark fur would be more obvious to its prey, who would more easily avoid him. The other white ones can blend in better and have a less chance of being detected by prey.
Organisms have genetic variation
The conditions change
The ones better at coping... survive
Survivors breed and pass on their variation
natural selection occurs
Some bacteria are more resistant
Antibiotic is added
Some bacteria survive
The survivors reproduce
Low levels of antibiotic remain
Charles Darwin
Hope I helped
Complete question
- It has to be E. coli because it is positive for gapA
- It can't be Salmonella, because it is negative for the invA marker but still makes people sick
- It has to be used because it is positive for the apeE marker
Answer:
<u>1. It can't be Salmonella, because it is negative for the invA marker but still makes people sick </u>
- A combination of positive results from the multiplex PCR inva, apee and gapa is used to definitively identify Salmonella.
- Pathogenic, or disease causing Salmonella is definitely not present, as inva is required for it to be pathogenic. The test did not detect the inva sequence, thus it is truly negative for this particular pathogen.
<u>2. It has to be E. coli because it is positive for gapA </u>
- E. coli may be present, as gapa was detected- a presumptive positive. However, this may need to be definitively determined through further methods of sample analysis, such as 2D-gel electrophoresis.
- apee may belong to another type of bacteria present within the initial sample, or there may be sample contamination
Explanation:
Polymerase chain reactions, PCRs are a form of nucleic acid amplification testing NAAT that exploit the mechanism of transcription by using a thermostable DNA polymerase. These require a sample of genetic material such as RNA or DNA; specific regions of the gene sequence are targeted for replication by primers. In the presence of these specific gene sequences, the primers make billions of copies of the sequences.
However, if these gene sequences are absent, the primers are not capable of identifying and amplifying the sequence. This reaction is highly specific. Positives obtained have a high chance of being true positives and negatives have a high chance of being true negatives
.
Pathogens or infectious agents that are capable of causing disease i.e. making people sick. Both E. coli and Salmonella are genuses of enteric bacteria capable of causing disease via fecal contamination. Common symptoms include
- abdominal cramps
- vomiting
- fever
- diarrhea
This test would include primers for the detection of each sequence: gapa, apee, inva. Salmonella's inva was not detected, thus it is not present.
Further steps may include a 2 D gel electrophoresis- here an electrical current is utilized to separate bands of DNA within the sample. This should correspond with an expected DNA size in base pairs or bp for E.coli- this should be determined by running the sample in the gel with a positive control, containing genetic material for E coli, and a negative control, of purified water to determine contamination.