Tonya used a microscope to observe five kinds of organisms in a sample of pond water. she wants to identify each organism using the dichotomous key below.

Where do homologous chromosomes exchange genetic material through crossing over?               a.  chlorophyll    b.  centrosomes    c.  centromeres    d.  chiasma

1. the passing of is the basis of heredity. 2. our encode the instructions that define our traits. 3. each of us has thousands of genes, which are made of and reside in our chromosomes. 4. in addition to our genes, the we live in also define our traits. 5. humans have two complete sets of chromosomes. 6. when parents conceive a child, each parent contributes set of chromosomes. 7. every child receives of its chromosomes from the mother and half from the father. 8. this transfer takes place at when the father’s sperm joins the mother’s egg. 9. while most cells in our bodies have two sets of chromosomes, or a total of egg and sperm each have chromosomes. 10. when egg and sperm unite they create a single cell called a 11. each parent contributes complete set of chromosomes to their child. 12. since the parents contribute the chromosomes to each new child, every child inherits a unique set of chromosomes. 13. as a result, every baby will have a combination of traits.

Acell in the human nervous system whose primary function is to form myelin and the blood-brain barrier, respond to injury, remove debris, and enhance learning and memory is called a(n) cell.