Why is dna called the "double helix"? select one: a. its structure was discovered by two workers, james watson and francis crick, a doubling of research effort at a building informally called the "helix" at cambridge university. b. dna is double stranded, with the two strands both in the form of a helix entwined around each other like strands of a rope. c. when dna interacts with rna, the two molecules form a twisted double strand. d. it seemed like a catchy name even though it has nothing to do with the structure of dna?

Alichen is an organism that structurally appears to be a single organism. but a lichen is actually two different organisms—a fungus and green algae—living together as one organism. the fungal partner derives its nutrition from the photosynthesizing algae. how does a lichen differ in its photosynthetic activity from elysia chlorotica, the sea slug that’s considered to be a photosynthesizing animal? a. in lichens, the fungi photosynthesize on their own, while elysia chlorotica forms a relationship with a photosynthesizing plant. b. in lichens, the relationship with the algae lasts throughout the life cycle, but in elysia chlorotica, the relationship occurs only during the immature juvenile stage of the slug’s life cycle. c. lichens can photosynthesize only because of the living algal partner, while elysia chlorotica incorporates chloroplasts from algae into its cells. d. in lichens, the association between the fungi and algae is permanent, while elysia chlorotica associates with a photosynthesizing organism only when it requires food.

7th grade question (easy) look at the diagram of the food web. the arrows mean eaten by. what would happen if the number of snakes went down? answer choices are in the image.

In a cladogram' when does a group of organisms branch off