Why doesn't a flatworm have a circulatory system?
a. The animal is flat enough to permit effective gas exchange by diffusion.
b. There is not enough room for a circulatory system.
c. The animal lacks muscles, so it could not have a heart to pump blood.
d. Only bilaterally symmetrical animals need a circulatory system.
e. Only vertebrates have circulatory systems.
a
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The left side of the heart and the arteries and veins in the body tissues make up the ________ circuit
Fill in the blank(s) with correct word
The approach to estimating phylogenetic trees is most like the approach of which species concept?
A) morphological species concept B) biological species concept C) phylogenetic species concept
Which of the following is acellular?
A. virus B. bacterium C. fungus D. protozoan
Your friend is concerned because although she has never been pregnant, her breasts are producing milk. When she went to the doctor, he sent her to the MRI lab for a brain scan. She was too embarrassed to ask the doctor why. What do you tell her?
A. "LH and FSH from the posterior pituitary stimulate milk production. The doctor wants to rule out excess levels of estrogen in the pituitary stalk." B. "The MRI technician must have mixed up your patient records. He should have done a thoracic scan instead." C. "Prolactin from the anterior pituitary stimulates milk production. The doctor probably wants to rule out a pituitary tumor." D. "They were actually scanning your thyroid gland, not your brain. Are you getting enough iodine in your diet?"