Which of these describes a quantitative observation? a) an observation of the phenomenon itself b) an observation of the relative size of something c) an observation of an effect the phenomenon has d) an observation that has a number associated with it asap! 20 points!

How is ribosomal rna useful as a molecular clock? a. a large portion of the dna ring is not vital to structure or function, allowing it to accumulate neutral mutations. b. its rate of mutation increases over time as organisms continue to evolve and differentiate from each other. c. a slow mutation rate makes it useful for determining evolutionary relationships between ancient species. d. it is only found in select organisms, making it easier to compare relationships between species that have it.

1. watermelon, papaya, oranges, bananas, and lemons are included in this food group. vitamin c 2. you need 6 or more servings of this food group each day vitamins d and a 3. found in fruit and keeps blood vessels healthy calcium 4. vitamins found in milk bread and grain 5. a mineral that strengthens bones fruit

Ascientist is conducting an investigation that involves water, silver, carbon dioxide, and oxygen gas which group of statements best describes all of the materials he is using in the investigation?