Answer:
invasive species are a problem both in anthropogenically altered and natural environments
Explanation:
An invasive species can be defined as a non-native species introduced into a new environment which then becomes abundant. Only in the US, it is believed that there are approximately 4,000 invasive species (some examples include the feral pigs, grey squirrels, European rabbits, etc.). In general, invasive species have a negative impact on the ecosystem, especially by displacing native species and thereby altering the trophic chain. In anthropogenically altered environments (anthromes), human beings are considered to be an invasive species.
Explanation:
Wind energy, or wind power, is created using a wind turbine, a device that channels the power of the wind to generate electricity. The wind blows the blades of the turbine, which are attached to a rotor. The rotor then spins a generator to create electricity . Wind energy is a renewable energy source that is clean and has very few environmental challenges. Wind power actually starts with the Sun. In order for the wind to blow, the Sun first heats up a section of land along with the air above it. That hot air rises since a given volume of hot air is lighter than the same volume of cold air. Cooler air then rushes in to fill the void left by that hot air and voila: a gust of wind. The Office of Energy Efficiency and Renewable Energy describes a wind turbine as “the opposite of a fan.” Simply stated, the turbine takes the energy in that wind and converts it into electricity. So how does it do that? First, the wind applies pressure on the long slender blades, usually 2 or 3 of them, causing them to spin, much like the wind pushes a sailboat along its path through the water. The spinning blades then cause the rotor, or the conical cap on the turbine, and an internal shaft to spin as well at somewhere around 30 – 60 revolutions per minute. The ultimate goal is to spin an assembly of magnets in a generator which will, well, generate voltage in a coil of wire thanks to electromagnetic induction. Generators require faster revolutions, however, so a gear box typically connects this lower speed shaft to a higher speed shaft by increasing the spin rate to around 1000 to 1800 revolutions per minute. These gear boxes are costly as well as heavy, so engineers are looking to design more “direct-drive” generators that can work at the lower speeds.
A
A haploid cell formed in the male seminiferous tubules
The reproductive tissues of male and female humans develop similarly in utero until a low level of the hormone testosterone is released from male gonads. Testosterone causes the undeveloped tissues to differentiate into male sexual organs. Primitive gonads become testes; other tissues produce a penis and scrotum in males.
In unicellular organisms such as bacteria, mitosis helps in asexual reproduction as it produces an identical copy of the parent cell. ... In the case of multicellular organisms, mitosis helps in growth and repair by producing more number of identical cells.
Answer:
The options
a. New combinations of genes yielding genotypes of greater fitness
b. Few heterozygotes because of underdominance
c. Frequency-dependent selection, leading to fluctuations in fitness
d. Heterozygotes with greater fitness, owing to overdominance
e. A random assortment of genotypes because of genetic drift
The CORRECT ANSWER IS b.
b. Few heterozygotes because of under dominance
Explanation:
In genetics, underdominance (at times called "negative overdominance") is the opposite of overdominance.
It is the selection against the heterozygote, that leads to disruptive selection and divergent genotypes. It occurs in cases of inferior and reduced fitness (As in our case study, it is the different chromosomal fusions and inversions)
of the heterozygotic genotype to the dominant or recessive homozygotic genotype. It is unstable as it causes fixation of either allele.
Another example is the African butterfly species Pseudacraea eurytus, which makes use of Batesian mimicry to avoid predation. This species carries two alleles that gives a coloration that is alike to a different local butterfly species that is harmful to its predator. The butterflies who are heterozygous for this trait are observed to be intermediate in coloration and thus encounter an higher risk of predation and a decrease in the total fitness.
