Why can a accepted hypothesis be rejected at a later date

Freckles are a dominant trait in humans. both of the girls have the genotype ff for freckles. if either one marries a man with no freckles, what are the chances that their children will have freckles?

What is the compliment dna strand to the following sequence: ttgactaggcta

Agroup of plant cells was exposed to radiation, which damaged the chloroplasts and caused them to lose function. if the mitochondria were unharmed, what would happen to the overall function of the plant cells? a. the cells would not be able to make food, but would be able to release energy from biomolecules. b. the cells would not be able to replicate dna, but would be able to break down waste. c. the cells would not be able to break down waste, but would be able to replicate dna. d. the cells would not be able to release energy from biomolecules, but would be able to make food.