Bio-Midterm (8-9)

Platelet-derived growth factor (PDGF) is a signaling molecule that functions in which of the following types of cell signaling?

Paracrine

Why do the functions of many receptor kinases depend on the fluid nature of the plasma membrane?

The receptor monomers must move together and dimerize to be activated.

Which of the following is a button-like point of attachment formed by the linking of integrins to intermediate filaments inside the cell and their binding to a protein of the extracellular matrix on the outside of the cell?

hemidesmosome

In a thylakoid membrane, absorbed light energy is passed from one chlorophyll molecule to another until it is:

passed to a reaction center

The energy required to drive the synthesis of the majority of the ATP generated during aerobic respiration comes most directly from:

the flow of protons through an ATP synthase complex.

In plants, the ultimate electron donor in photosynthesis is ________

water

A photosynthetic electron-transport chain captures in chemical form approximately what percentage of the sun's usable energy arriving at the surface of a leaf?

24%

How many CO2 molecules must enter the Calvin cycle for each molecule of triose phosphate that can be exported from the chloroplast?

3

Approximately what percentage of the sun's output is available for photosynthesis?

40%

A protein on a cell surface that binds to a signaling molecule is an example of which of the following elements of cellular communication?

A receptor protein

Which one of the following is NOT a product when photosystem II oxidizes a molecule of water?

Carbon Dioxide

A cell's particular shape is largely determined by:

Cytosolic proteins that assemble into structures called cell junctions. A mesh of proteins and polysaccharides in the extracellular matrix Cytoskeletal protein networks in the cytoplasm

Which of the following is TRUE about the Delta protein

Delta directly signals to a Notch transmembrane protein in adjacent cells Delta directs adjacent cells to differentiate into glial cells. Delta is a transmembrane protein found in embryonic brain cells Delta is produced by embryonic stem cells as they differentiate into neurons in the brain.

Which one of the following is a candidate for the FIRST electron donor

Fe2+

Kohler and Lipton first discovered platelet-derived growth factor by observing that fibroblasts:

Grew better in cell culture when blood serum was added to the growth medium instead of blood plasma.

Which type of receptor is involved in rapid responses of muscle cells and neurons?

ligard-gated ion channel

Protons in a chloroplast flow through an ATP synthase from the:

thylakoid lumen to the stroma

8) Light energy is converted to chemical energy in the:

thylakoid membrane

Which of the following is a mesh-like attachment between cells formed by binding of transmembrane proteins of one cell to the same protein type on the adjacent cell, preventing substances from passing between cells?

tight junction