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: 3506

#Unit 11. Evolution and Behavior

An altruist provides help worth 9 units of fitness to a recipient, at a personal cost of 2 unit of fitness. As per kin-selection theory, the minimum value of genetic relatedness between the actors and the recipients that is necessary to maintain altruism in the population is

#Question id: 3507

#Unit 11. Evolution and Behavior

Rank the following from most general to most specific:

A. gametic isolation

B. reproductive isolating mechanism

C. pollen-stigma incompatibility

D. prezygotic isolating mechanism

#Question id: 3508

#Unit 11. Evolution and Behavior

In these cases, females would indirect benefit by choosing the male that having which of following attribute 

a. can provide the best care

b. provide no care, but maintain territories

c. Large males, have probably been successful at living long, acquiring a lot of food and resisting parasites and disease

d. The long tail of the peacock

#Question id: 3509

#Unit 8. Inheritance Biology

Principle of independent assortment apply for those gene that is

#Question id: 3510

#Unit 8. Inheritance Biology

Assume that the trihybrid cross AA BB RR X aa bb rr is made in a plant species in. What proportion of F2 progeny would be expected to be homozygous for all three genes when independently assort?

#Question id: 3511

#Unit 8. Inheritance Biology

What proportional of one round and two wrinkle seed if random selected 3 seed from various seed produced from monohybrid test cross?