How does cystic fibrosis increase the risk of respiratory infections such as bronchitis and pneumonia? a. by causing mucus to build up in airways.

b. by destroying cells of the immune system.

c. by reducing blood flow to the lungs.

d. by increasing air flow to the lungs.

Which of the following is not a main characteristic that scientists focus on when determining which kingdom an organism belongs to

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.

Development of new communities in disturbed environments, such as a burned or a clear cut forest, is called