Bacteria are very small single-celled organisms that lack a nucleus. although bacterial cells are less complex than the cells that make up the human body, bacteria are very important to human health. which statement best summarizes how bacteria affect human health?
a)
bacteria cause disease in humans.
b)
bacteria are beneficial to humans.
c)
bacteria rarely affect human cells because they are so much smaller.
eliminate
d)
some bacteria are beneficial to humans and some bacteria are harmful.

Explain why phospholipid molecules form a bilayer. (3 marks)

Mouse liver cells were homogenized and the homogenate subjected to equilibrium density-gradient centrifugation with sucrose gradients. fractions obtained from these gradients were assayed for marker molecules (i.e., molecules that are limited to specific organelles). the results of these assays are shown in the figure. the marker molecules have the following functions: cytochrome oxidase is an enzyme involved in the process by which atp is formed in the complete aerobic degradation of glucose or fatty acids; ribosomal rna forms part of the protein-synthesizing ribosomes; catalase catalyzes decomposition of hydrogen peroxide; acid phosphatase hydrolysis monophosphoric esters at acid ph; cytidylyltransferase is involved in phospholipid biosynthesis; and amino acid permease aids in transport of amino acids across membranes. a) name the marker molecule and give the number of the fraction that is most enriched for each of the following cell components: lysosomes; peroxisomes; mitochondria; plasma membrane; rough endoplasmic reticulum; smooth endoplasmic reticulum.

How does photosynthesis show the conservation of mass and energy?