Which structure allows gases and nutrients in and out of the cell

You have just sequenced a new protein found in mice and observe that sulfur-containing cysteine residues occur at regular intervals. what is the significance of this finding? it will be important to include cysteine in the diet of the mice. cysteine residues are required for the formation of α helices and β pleated sheets. cysteine residues are involved in disulfide bridges that form tertiary structure. cysteine causes bends, or angles, to occur in the tertiary structure of proteins.

Grasses--> mice--> cats--> coyotes suppose 10,000 units of energy are available at the level of the grasses. what is the total number of energy units lost by the time energy reaches the coyote?

Which of the following is a true statements about viruses? viruses have no nucleus. viruses are alive. viruses have a cell membrane. all viruses are deadly.