In order to support his theory of evolutionary change, charles darwin concentrated his studies on the many species of finches in the galapagos islands. darwin noted that many of the birds had different shapes and styles of beak. what is a possible explanation for what darwin observed? a) the birds had beaks that were adapted for feeding differently. b) some birds had been injured by predators and were poor competitors. eliminate c) people had bred the bird to have beaks with varied shapes and sizes. d) the birds had different beaks because females preferred certain beak shapes over others.

The correct answer is - A) The birds had beaks that were adapted for feeding differently.

The finches on the Galapagos Islands all derive from a small group of finches that were the same and managed to come to these islands. Over time, they started to develop numerous types of beaks, thus they started to diversify. The reason for this was that there were multiple free niches in the food chain on the Galapagos Islands, so the finches started occupying them. Some developed beaks that are more suitable for eating fruits, some that are more suitable for eating seeds and nuts, some that are more suitable for eating insects etc. All that different types of food choices contributed that they develop a beak type that will enable them to be more efficient in the consumption of their preferable food source.

the answer is: the „power stroke“ step.

muscle contraction can be divided into a few steps:

1. the release of ach (acetylcholine) in the synaptic cleft, binding of ach for its receptor and consequently opening of the ca channels.

2. the release of ca, binding of ca for the troponin

3. troponin shifting the tropomyosin, which was blocking the active site on the actin

4. myosin heads attaching to actin by breaking down atp to adp+ pi

5.   formation of the ‘cross-bridge’ on the active site of the actin filament by myosin head

6. “power stroke” -the cross bridge pulls actin, which slides over the myosin

9.     7. the release of adp completes the cross-bridge movement and atp attaches to myosin, breaking the actin-myosin cross bridge.

energy per photon is e = h*c / λ  

e = 6.63*10^-34 * 3*10^8 / 6*10^-7 j = 3.315*10^-19 j  

nr. of photons = 10j / 3.315*10 = ^-19 j per photon = 3.02*10^19 photons