Question

1. how does blood return to the heart after circulating through the body?

a. through lymphatic vessels
b. through veins
c. through arteries
d. through capillaries

1. what is the semi - liquid substance formed in the stomach after food is mixed with digestive juices?

a. bolus
b. bile
c. feces
d. chyme

1. what substance does the stomach secrete to help break down proteins?

a. hydrochloric acid
b. amylase
c. lipase
d. bile

1. what is the role of the pulmonary veins?

a. to carry oxygenated blood to the lungs
b. to bring oxygenated blood back to the heart from the lungs
c. to transport waste products to the kidneys
d. to carry deoxygenated blood to the lungs

1. the formation of germ layers - ectoderm, endoderm, and mesoderm - takes place during which developmental process?

a. implantation
b. gastrulation
c. ovulation
d. cleavage

1. what is the myelin sheaths role in the nervous system?

a. to receive signals from other neurons
b. to send neurotransmitters to receptors
c. to prevent electrical signals from leaking

d. to increase the speed of signal transmission along the axon

1. how many lobes does the right lung have?

a. three
b. four
c. one
d. two

Explanation:

1. Veins are the blood vessels that carry deoxygenated blood back to the heart after it circulates through the body's tissues.
2. When food mixes with stomach digestive juices, the resulting semi-fluid mixture is called chyme.
3. The stomach secretes hydrochloric acid, which helps break down proteins and creates an acidic environment for digestive enzymes.
4. The pulmonary vein is the only vein that carries oxygenated blood, transporting it from the lungs back to the heart.
5. Gametes (sperm/egg) form through meiosis, a cell division process that reduces the chromosome number by half to produce haploid sex cells.
6. The myelin sheath insulates nerve axons, which speeds up the rate of electrical signal (nerve impulse) transmission along the axon.
7. Each human lung is divided into three lobes.

Answer:

1. b. Through veins
2. d. Chyme
3. a. Hydrochloric acid
4. b. To bring oxygenated blood back to the heart from the lungs
5. d. Meiosis
6. d. To increase the speed of signal transmission along the axon
7. a. Three