The Roberts family has had a large family garden for several years. Every autumn, after the first frost, they pull up the dead plants and cover the garden rows with black plastic. When it is spring and planting time, they plant seeds though holes they have poked in the plastic. Why do the Roberts use the plastic covering? A. The black plastic keeps the weeds from growing in the bare soil.
B. The black plastic keeps the soil warm so the seeds will grow in the spring.
C. The black plastic helps the organisms that live in the soil survive the winter.
D. The garden space will be covered with grass and animals will graze in the area.

they deliver oxygen to the blood

the match duh

explanation:

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!