Biology Organismal Biology & Physiology Flashcards

Which structure in the human kidney is responsible for filtering blood to form the initial filtrate?

Answer: Glomerulus

The glomerulus is the capillary network where blood pressure drives water and small solutes into the Bowman's capsule to form the glomerular filtrate.

What is the primary function of the loop of Henle in the nephron?

Answer: Creating an osmotic gradient in the renal medulla

The loop of Henle establishes a hyperosmotic gradient in the renal medulla that allows the collecting duct to concentrate urine.

In flowering plants, which tissue transports sugars produced by photosynthesis from leaves to other parts of the plant?

Answer: Phloem

Phloem conducts organic compounds such as sucrose from source tissues (leaves) to sink tissues (roots, fruits) via pressure-flow.

Which type of muscle tissue is under involuntary control and found in the walls of the digestive tract?

Answer: Smooth muscle

Smooth muscle is non-striated, involuntary, and lines hollow organs such as the intestines where it drives peristalsis.

What hormone do chief cells of the stomach secrete, and what is its function?

Answer: Pepsinogen; is activated to pepsin which digests proteins

Chief cells secrete pepsinogen, an inactive zymogen that hydrochloric acid converts to pepsin, which cleaves dietary proteins.

Which layer of the skin contains the melanocytes that produce melanin?

Answer: Stratum basale

Melanocytes reside in the stratum basale (deepest epidermal layer) and transfer melanin granules to surrounding keratinocytes.

During a sympathetic 'fight-or-flight' response, which effect on the heart would you expect?

Answer: Increased heart rate and increased contractility

Norepinephrine released by sympathetic neurons binds β1 receptors, increasing both heart rate (chronotropy) and contractility (inotropy).