#Question id: 6966
#Unit 5. Developmental Biology
During gastrulation in the frog, the very first cells to move into the interior of the embryo through the blastopore come from the surface layer of cells in the marginal zone; they will become:
#Question id: 18716
#Unit 13. Methods in Biology
#Question id: 2585
#Unit 2. Cellular Organization
Which of the following is the correct sequence that describes the excitation and contraction of a skeletal muscle fiber?
A. Tropomyosin shifts and unblocks the cross-bridge binding sites.
B. Calcium is released and binds to the troponin complex.
C. Transverse tubules depolarize the sarcoplasmic reticulum.
D. The thin filaments are ratcheted across the thick filaments by the heads of the myosin molecules using energy from ATP.
E. An action potential in a motor neuron causes the axon to release acetylcholine, which depolarizes the muscle cell membrane.
#Question id: 836
#Unit 1. Molecules and their Interaction Relevant to Biology
To predict the structure of any protein the most simplest and reliable approach is,
#Question id: 11249
#Unit 10. Ecological Principles
Choose the density-dependent factor that will slow population growth as population size increases.