Answer:
1. Another word for chemical weathering is b. disintegration
Chemical weathering is a process by which the rocks are broken down into parts and sediments by the action of a chemical agent such as alkali or acid. The disintegration can be a natural process by which a solid body is broken down into parts or subparts.
2. d. moving water is not an agent of chemical weathering agent.
The chemical weathering can be caused by the agents like lichens which secretes acid on the rock surface and causes it's disintegration, acid rain and salt water are chemical agents that can cause the disintegration of the rock but moving water will have little influence on the hard rock surface.
3. c. chemical weathering is a process which turns rocks and minerals into new substances. The chemical weathering process brings change in the chemical composition of the rocks due to the action of the weathering agents hence, on disintegration of rocks new substances are formed.
The correct answer should be A. spores
Ferns don't have seeds and they reproduce using spores. Cones have seeds in them and seeds fall out. Pollen enters a flower and then the flower becomes a fruit. This is sexual reproduction of plants. Since ferns don't have this, they have to reproduce with spores.
Answer:
Selection is a directional process that leads to an increase or a decrease in the frequency of genes or genotypes. Selection is the process that increases the frequencies of plant resistance alleles in natural ecosystems through coevolution, and it is the process that increases the frequencies of virulence alleles in agricultural ecosystems during boom and bust cycles.
Selection occurs in response to a specific environmental factor. It is a central topic of population and evolutionary biology. The consequence of natural selection on the genetic structure and evolution of organisms is complicated. Natural selection can decrease the genetic variation in populations of organisms by selecting for or against a specific gene or gene combination (leading to directional selection). It can increase the genetic variation in populations by selecting for or against several genes or gene combinations (leading to disruptive selection or balancing selection). Natural selection might lead to speciation through the accumulation of adaptive genetic differences among reproductively isolated populations. Selection can also prevent speciation by homogenizing the population genetic structure across all locations.
Selection in plant pathology is mainly considered in the framework of gene-for-gene coevolution. Plant pathologists often think in terms of Van der Plank and his concept of "stabilizing selection" that would operate against pathogen strains with unnecessary virulence. As we will see shortly, Van der Plank used the wrong term, as he was actually referring to directional selection against unneeded virulence alleles.
