Water at about 4°c (39°f) is more dense than water at 0°c (32°f). why would the living organisms in the lake die if the water at the freezing point was denser than the water at 4°c?

the water would freeze across the surface of the lake, blocking sunlight necessary for photosynthesis.
the water would freeze across the surface of the lake, blocking the dissolving of oxygen and nutrients.
the freezing water would sink before it could freeze, preventing the lake water from freezing.
the freezing water would sink to the bottom and freeze the lake water from the bottom up.

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.

Earthquakes a.created the rock in arches utah b.can be caused by volcanic eruptions c.are caused by tsunami waves d.wear mountains down into hills

Describe how viruses and bacteria can be used as biological weapons. what are some of the potential threats and potential benefits? do you agree with the use of viruses and bacteria as biological weapons? why or why not?