The full-length (i. e., containing the entire protein-coding region) cdna for a specific eukaryotic gene in humans is 1500 nucleotides long. you screen a pig genomic library with this cdna and isolate two genomic clones of different lengths. both clones are sequenced and found to be 1900 and 2100 nucleotides long from start codon to stop codon. screening of genomic libraries of several other organisms reveals that all of them contain only one genomic clone -- pigs seem to be the exception to the rule here. what evolutionary events might have led to the presence of two genomic clones in pigs, and the discrepancies in their length compared to the cdna probe? how is this representative of a general type of occurrence in molecular genetic evolution?

Sally and sue were investigating the topic of friction in science. they used a small car and a ramp as seen in the picture to test what they were learning. they knew that they slipped easily on waxed floors but not on carpet, so they decided to change the material on the surface of the ramp to see what happened. they planned to use glass, carpet, aluminum foil, and sandpaper and run the car down the ramp over each surface. what would be the best research question to guide the girls' experiment? a) does the amount of surface area affect the friction on the moving car? b) will the car travel fastest on the glass surface? c) how does the angle of the ramp affect the speed of the car? d)do rougher surfaces tend to create more friction than smooth surfaces?

The mammal pictured below is a silvery mole rat. which statement is an inference based on the picture? the animal is ugly. the animal has hairless feet with sharp claws. the animal has prominent upper and lower incisor teeth. the animal likely has poor vision since its eyes are so small.

How can you tell the difference between rough er from smooth er?