In ecology, allogenic succession is mediated by the abiotic components of the ecosystem, while the autogenic succession refers to the succession, which is mediated by the biotic components of an ecosystem.
A volcanic eruption wiping out an entire island is an example of allogenic succession.
A soybean crop helping in nitrogen fixation, leading to the development of other species is an illustration of autogenic succession.
A tsunami devastating all the living organism in a habitat is an example of allogenic succession.
Oak trees preventing the growth of smaller sun-seeking shrubs is an example of autogenic succession.
Answer:
Option A, Hormones are controlled by a feedback loop; information about a system is sent back to the controller of the system to improve its function.
Explanation:
Negative feedback loop controls the hormone production and release. This is done by eliciting the release of substances till a certain level after which the stop signal is activated thereby preventing further release. By this method, concentration of hormones in blood is maintained within the narrow range.
For example – Thyroid hormones is released when the anterior pituitary signals the thyroid. This continues till the hormones in the blood reach the threshold level. Once the threshold level is reached, hypothalamus receives a feedback and then signals anterior pituitary to inhibit further signaling to the thyroid
Hence, option A is correct
Answer and Explanation: The farmer has a pure-breeding line of tomato means the farmer has a tomato with genotype FFrrtt while the other line of tomato has genotype ffRRTT.
The cross between these lines gives a F1 generation of heterozygous full, red and axial or FfRrTt.
With an individual of F1 crosses with another individual of F1, the Punnet Square will be:
FfRrTt x FfRrTt
1) Dividing each characteristics, for simplicity:
F f
F FF Ff
f Ff ff
R r
R RR Rr
r Rr rr
T t
T TT Tt
t Tt tt
Analysing Punnett squares, we notice the line wanted (ffrrTT) will be produced, when an individual of F1 generation cross with another individual with the same generation.
