Some photosynthetic bacteria (e. g., purple sulfur bacteria) have only photosystem i, whereas others (e. g., cyanobacteria) have both photosystem i and photosystem ii. which of the following might this observation imply?

What links the two strands in a dna helix together in the middle? a. phosphate groups b. sugar rings bonded together c. proteins d. bases with hydrogen bonds

Need will mark ! which features are created by groundwater erosion and deposition? check all that apply. a. stalagmitesb. sinkholesc. rillsd. stalactites e. gullies f. rivers

After reading the paragraph below, answer the questions that follow. researchers have created a robot that has a very thin leg that is moved by cardiac (heart) cells contracting in unison. the robot, made of a polymer similar to that used in making contact lenses, is bathed in heart cells with supporting cells, which then attach to the robot and provide movement as they contract. all of the cardiac cells working together can cause the robot leg to move in a way that individual cells could not. this is an example of a. emergent properties of cells. b. energy flow through an ecosystem. c. adaptation. d. internal environment regulation.