BIO-100 F035 Chapter 3 HW

Which choice describes diffusion?

The movement of a substance from a region where it is more concentrated to a region where it is less concentrated, down its concentration gradient.

Cell theory began to develop in 1839, following the research of Matthias Schleiden and Theodor Schwann into plant and animal tissues. Both the botanist Schleiden and the physiologist Schwann noticed that every organism they viewed under a microscope, whether plant or animal, was composed of cells. Their observations that all living species are made up of one or more cells led to the early formation of cell theory. Which tenet of cell theory is described by the paragraph about the historical observations of cells?

All organisms are composed of one or more cells.

Which statements describe examples of facilitated diffusion?

1. An inner ear hair cell allows potassium ions to flow down their concentration gradient after sound waves stimulate a membrane protein. 2. An erythrocyte low on glucose replenishes its supply using a membrane protein to transport glucose down its concentration gradient. 3. A neuron allows potassium ions to leave the cell down their concentration gradient using a membrane channel.

A few unidentified seeds were found in a sealed clay jar during an archaeological dig. Radiocarbon dating showed that the seeds were 725 years old. When the seeds were planted, plants grew from them. Based on cell theory, what statements can confidently be made regarding these unidentified plants and seeds?

1. Both the seeds and mature plants are composed of cells 2. Living cells inside the seeds divide to generate the new plant cells.

Which statements about lysosomes are true?

1. Lysosomes break down damaged organelles for recycling 2. Lysosomes are lipid spheres filled with digestive enzymes. 3. Lysosomes are responsible for programmed cell death.

Facilitated diffusion is a type of passive transport that allows solutes to move across the plasma membrane of a cell. Which statements describe facilitated diffusion?

1. Solutes move across the membrane down their concentration gradient through specialized membrane proteins. 2. Small, charged molecules and ions move down their concentration gradient into a cell through proteins in the plasma membrane.

Which statements are properties of protein‑based active transport?

1. Substances move from an area of lower concentration to an area of higher concentration. 2. Substances cross the plasma membrane by being pumped through a protein using ATP.

Select the descriptions that apply to the ribosome.

1. a cellular structure that is composed of both RNA and protein 2. a molecular structure that is the site of protein synthesis

One of the key considerations when developing antibiotics is targeting bacteria without harming the infected individual. Protein synthesis in bacteria and eukaryotes are different enough that this is a good target for antibiotics that inhibit translation machinery. In fact, antibiotics that inhibit bacterial translation can do so in different ways. Select the specific mechanisms by which certain antibiotics interfere with translation.

1. acts as a peptidyl‑transferase complex competitive inhibitor 2. binds to the ribosome and blocks subsequent translation

Which of the statements are true of endosymbiotic theory?

1. states that an ancestral eukaryotic cell engulfed an aerobic protobacteria 2. explains why chloroplasts contain a double membrane 3. explains the origin of some eukaryotic organelles, such as mitochondria

Which eukaryotic cell parts is found in the cytoplasm, provides structure and support to the cell, and is composed of interconnected protein fibers?

cytoskeleton