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zheka24 [161]
3 years ago
6

Studies in which the suprachiasmatic nucleus (SCN) was surgically removed from laboratory mammals demonstrated that the SCN is r

equired for circadian rhythms. But these studies did not reveal whether circadian rhythms originate in the SCN. To answer this question, researchers performed an SCN transplant experiment on wild-type and mutant hamsters (Mesocricetus auratus). For wild-type hamsters, the period between cyclic peaks in activity is 24 hours in the absence of external cues. Hamsters homozygous for the τ (tau) mutation have a period lasting only about 20 hours. In this exercise, you will evaluate the design of this experiment and propose additional experiments to gain further insight. The researchers surgically removed the SCN from wild-type and τ hamsters. Several weeks later, each of these hamsters received a transplant of an SCN from a hamster of the opposite genotype. These transplants restored rhythmic activity in 80% of the hamsters. For hamsters in which an SCN transplant restored a circadian rhythm, the researchers measured the circadian period. The results are shown in the graph. Each red line represents the change in the measured period for an individual hamster. Part A - Understanding the experimental design In a controlled experiment, researchers manipulate one variable at a time. What was the experimental variable in this study?
Biology
1 answer:
Alex777 [14]3 years ago
3 0

Answer:

yo no se

Explanation:

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Drupady [299]
<span>1. List five observations Darwin made about the Amblyrhynchus lizards.

a. They measure about 2-3 feet long.
b. They are cold-blooded.
c. They feed on crab and sea lion feces.
d. They are the only marine iguanas in the world.
e. Their nostrils are connected to salt glands that allow them to expel excess sea salt. 

</span><span>2. Describe two examples of structural adaptations that Darwin observed.

a. </span><span>Darwin discovered that finches in the Galapagos have thirteen different kinds of beaks. 
b. </span>Darwin observed two kinds of giant tortoises that are distinguished by the shapes of their carapaces (dome-shaped and saddle-shaped). 

3. <span>Describe two behavioral adaptations that Darwin observed.
</span>
a. <span>The marine iguanas have developed several ways of coping with the cold. At night, they huddle together for warmth. 
b. </span>In the face of famine, the marine iguanas have adapted by having the ability to shrink their body size. They are able to grow back to their original size once the food is supply increases.

4. <span>Explain how these observations influenced his theory of evolution?
</span>

These observations led Darwin to believe that if a certain trait is more advantageous in a specific environment, then the carriers of that trait are more likely to survive into adulthood and to generate offspring than those who do not have that trait. Eventually, the advantageous traits for a species will proliferate. Darwin later called this as "survival of the fittest".

6 0
3 years ago
Read 2 more answers
TRUE or FALSE. | There is a gravitational attraction force between you and this computer.
kolbaska11 [484]

Answer:

true

Explanation:

Since gravitational force is inversely proportional to the square of the separation distance between the two interacting objects, more separation distance will result in weaker gravitational forces. So as two objects are separated from each other, the force of gravitational attraction between them also decreases.

5 0
3 years ago
Protists vary in structure and function more than any other group of organisms. However, here are some common traits: a.All have
Sophie [7]

Answer:

a. eukaryotes

b. unicellular

c. autotrophs; heterotrophs

Explanation:

Protists represent a separate kingdom of eukaryotic organisms (ie., organisms whose cells have a nucleus). The most important features of protists include: 1- they are unicellular organisms, 2-contain mitochondria, 3-can be parasites, and 4-generally live in optimal conditions in moist or aquatic environments. In the past, protists were divided into Protozoa (animal-like organisms) and Protophyta (plant-like organisms), which nowadays we know are heterotrophic (also often parasitic) and photosynthetic protists, respectively.

3 0
3 years ago
Consider the model of natural selection. In order for the end result to be dark gray circles, what do you know about the populat
Sunny_sXe [5.5K]
B.https://www.mansfieldct.org/Schools/MMS/staff/hand/genNaturalselection06.htm this is where I got my source.
6 0
3 years ago
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Please help with this question I am so confused!​
Angelina_Jolie [31]

Answer:

prokaryotic cells only

Explanation:

6 0
3 years ago
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