Which statement explains the most realistic way to model energy flow in an ecosystem?

A food chain is most realistic because many organisms eat one type of food, and energy moves through a single pathway.
A food chain is most realistic because many organisms eat a variety of foods, and energy moves through different pathways.
A food web is most realistic because many organisms eat one type of food, and energy moves through a single pathway.
A food web is most realistic because many organisms eat a variety of foods, and energy moves through different pathways.

Why was the sample heated in step 5? describe the chemical principles involved in the reasoning behind this step?

How does pregnancy begin? a) a placenta forms in the uterus b) a sperm reaches an egg in the fallopian tubec) the blastocyst differentiates into two cell types d) contractions begin in the uterine wallapex

In eukaryotes, genetic information is passed to the next generation by processes that include mitosis or meiosis. which of the explanations identifies the correct process and supports the claim that heritable information is passed from one generation to another? a. mitosis, followed by cytokinesis, produces daughter cells that are genetically different from the parent cell, thus insuring variation within the population. b. during mitosis, dna replication occurs twice within the cell cycle to insure a full set of chromosomes within each of the daughter cells produced. c. in asexual reproduction, a single individual is the sole parent and passes copies of its genes to its offspring without the fusion of gametes. d. single-celled organisms can fuse their cells, reproducing asexually through mitosis to form new cells that are not identical to the parent cell.