Why is halley's comet named after sir edmund halley? a. he was the first person to discover it. b. he calculated its orbit period correctly and estimated the time of its reappearance. c. he was dedicated to the field of astronomy. d. he was very famous at that time. e. he was the first to discover historical records of its observation.

Which of the following structures is not found in both plant and animal cells? a) chloroplast b) cytoskeleton c) ribosomes d) mitochondria

What was the land like over 500 million years ago? what was under the sea?

Select the correct answer. tay-sachs disease is caused by a mutation in the hexa gene located on chromosome 15. tay-sachs follows an autosomal recessive pattern of inheritance. with the of the diagram, identify which of the offspring will be an unaffected carrier. a diagram showing the genes of parents who are carriers of tay-sachs disease a. a, b, and c b. b and c c. a and d d. a e. d