Answer: Van der Waals forces
Explanation:
Van der Waals forces are weak intermolecular forces that depend on the distance between two particles. They are caused by correlations in the change in polarization between two nearby particles. To put it in other words, when a particle changes its polarization (becomes more positive on one end and more negative on the other), so does the adjacent particle, and the next one, and so on. This causes these particles to stick together weakly.
The tiny "hairs" increase the surface area of the gecko's feet in contact with the wall, which makes the bond stronger and allows it to support all of its weight.
Because experiments have shown that geckos stick well to both hydrophobic and hydrophilic surfaces, we can assume there aren't any hydrogen bonds present.
Ionic bonds can't be present either because geckos wouldn't stick to electrically neutral surfaces, as these bonds require charged molecules.
Answer:
A)Fixation. Nitrogen in its gaseous form (N2) can't be used by most living things
B) it can not be used because it most be converted or, ’fixed’ to a more useable form. To do this it goes through a process called fixation.fixation is the change in a gene pool from a situation where there exists at least two variants of a particular gene (allele) in a given population to a situation where only one of the alleles remains.
C) This form can be made more usable if it’s converted. It has to go through the process of fixation so the gene pool changes.
Explanation:
Species evolve independently possibly due to geographical isolations or behavioural isolations.
Geographical isolation includes the isolation of 2 groups of the same species. Since these 2 groups live in different locations, (e.g. a volcanic eruption resulting in a barrier between one side of an ocean and another side of the ocean), they will have different selection pressures in their different environments as well (e.g. one side of the ocean may have more sunlight and thus more underwater plantations than the other side of the ocean). Natural selection will eliminate those with disadvantageous characteristics (e.g. Fishes that only eat plants and nothing else on the side of the ocean with little plantations) with unfavourable alleles, and select for those with advantageous characteristics (e.g. Fishes are able to eat plants and other organic substances as well on the side of the ocean with little plantations) with favourable alleles.
Since the 2 groups have different selection pressures, natural selection will occur in different ways, selecting for and against different types of fishes with different types of alleles. Also, because of the barrier, they are not able to mate with each other, and there are no mixing of genes from one side of the ocean and the other side. They are genetically isolated. As genetic drift occurs over time, their gene pools become different from each other. Thus, they evolve independently.
Hope this helps! :)
Answer:
B is true .. atmosphere always changes day by day
The correct answer is - C) carotenoids.
The majority of the trees from the mid-latitude forests tend to shade their leaves in the autumn. This process occurs because of the seasonal changes in the climate, where the trees tend to be almost not-active during the winter, so in order to preserve as much energy and nutrients as possible they get read off their leaves.
It is not a sudden process, but it takes some time, where the leaves from the initial green color start to change to yellowish, than towards orange, reddish, or brownish before they fall.
The reason why this coloration appears in the leaves when the tree starts to process of shading them off are carotenoids. The carotenoids found in the leaves, the lutein and the beta-caroten, thorugh the xantophills and the flavonoids give a yellowish color to the leaves, thus we get the beautiful autumn colors and landscapes.
