Answer:
Salut!
- Light enters the eye through the cornea.
- Light travels to the macula within the retina.
- Rhodopsin absorbs light, and the Vitamin A changes shape.
- Vitamin A detaches from the rhodopsin, and some vitamin A is lost.
- Vitamin A from the bloodstream replenishes what is lost. The vitamin A returns to its original shape.
Explanation:
Retina is the part of the eye that contains photosensitive cells that capture light and produce the electrical signals that the brain perceives as images. These photosensitive cells are of two kinds:
Rods contain the photosensitive pigment, rhodopsin that is needed for vision at night or in dim light. Cones function in bright light.
Rhodopsin Bleaching:
Vision in bright or excessive light requires a process called rhodopsin bleaching which is the degradation of rhodopsin upon exposure to light. Upon contact with light, rhodopsin goes through structural changes characterized by the conversion of a pigment derived from Vitamin A, 11-<em>cis</em> retinal to all <em>trans</em> retinal. This chemical conversion initiates a photo-transduction reaction (reaction in which a photon of light is converted into electrical signals) that produces the electrical signals that travel to the brain via the optic nerve. The brain converts the electrical signals to images. This is followed by rhodopsin regeneration in the dark in which all <em>trans</em> retinal is converted back into 11 <em>cis</em> retinal.
Tsunami, I think, maybe a flood
Answer:
b. developing a hypothesis
Answer:
The next generation average time to flowering will be 98 days.
Explanation:
Before answering the question, we need to know a few concepts.
- Artificial selection is the selecting practice of a specific group of organisms in a population -that carry the traits of interest- to be the parents of the following generations.
- Parental individuals carrying phenotypic values of interest are selected from the whole population. These parents interbreed, and a new generation is produced.
- The selection differential, SD, is the difference between the mean value of the trait in the population (X₀) and the mean value of the parents, (Xs). So,
SD = Xs - X₀
- Heritability in the narrow-sense, h², is the genetic component measure to which additive genetic variance contributes. The heritability might be used to determine how the population will respond to the selection done, R.
h² = R/SD
- The response to selection (R) refers to the metric value gained or lost from the cross between the selected parents. R can be calculated by multiplying the heritability h², with the selection differential, SD.
R = h²SD
R also equals the difference between the new generation phenotypic value (X₁) and the original population phenotypic value (X₀),
R = X₀ - X₁
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Now that we know these concepts and how to calculate them, we can solve the proposed problem.
<u>Available data: </u>
- trying to decrease the maturation time in a population of sunflowers.
- the population mean time to flower is 100 days → X₀
- Chosen parental Plants mean flowering time is 90 days → Xs
- the narrow-sense heritability for flowering time is 0.2 → h²
According to what we sow previously, we need to find out the value of X₁, which reflects the next generation average time to flowering.
- We know that R = X₁ - X₀, so we need to clear this formula to calculate X₁
X₁ = R + X₀
We already know that X₀ = 100 days,
Now we need to calculate R.
We know that h² = 0.2,
Now we need to calculate SD
Xs = 90 days → Parentals media flowering time
X₀ = 100 → Population media flowering time
SD = Xs - X₀
SD = 90 - 100
SD = - 10 days
Knowing this, we can calculate R
o h² = 0.2
o SD = - 10
R = 0.2 x (-10)
R = - 2
- Finally, once we know the R-value we can calculate the X₁ value
X₁ = R + X₀
X₁ = - 2 + 100
X₁ = 98
