Answer:
The muscle tissue shortens to performs it's function which we know as muscle contraction
Answer:
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Explanation:
Answer:
According to Darwin's theory of evolution, new species evolved as a result of natural selection.
Explanation:
- Darwin proposed that speciation could readily occur through the prolonged action of Natural selection.
- Natural selection allows the 'survival of the fittest' i.e. a more fit organism will have a better chance of survival than the less fit one.
- The result of Natural selection could be positive,negative or balancing.
- Evolutionary process in which the genetic changes confer a higher fitness to increase frequency of the organism over time in population is called positive selection.
- Evolutionary process in which genetic changes decreases the organism's fitness resulting in its disappearance from the population is called Negative selection.
- It may happen that a mutation benefits hetero-zygotes but not homo-zygotes and alleles maintain a intermediate frequency in population.This evolutionary process is called balancing selection.
Answer:
In bryophytes, the sporophyte is minute and dependent on the relatively prominent and nutritionally independent gametophyte for resources. The moss gametophyte looks like a miniature herb, with tiny leaf-like photosynthetic organs. The gametophyte generation begins as a dormant spore, which germinates under appropriate conditions to produce filamentous and branching protonemal tissues. These form multicellular bud-like structures, each of which develops into a leafy shoot. The mature gametophytes produce male and female sexual organs, the antheridia and archegonia, respectively. The gametophyte is often sexually distinct, and plants are either male or female.
Each antheridium has an outer layer that encloses and protects thousands of motile sperm, which swim through available external water layer to the egg. Fertilization at the base of the cylindrical archegonium produces a diploid zygote which develops into an unbranched sporophyte. The sporophyte consists of a thin stalk attached to the gametophyte, and a capsule that encloses the sporophytic meiotic cells.
In recent years, the mosses Physcomitrella patens and Funaria hygrometrica have emerged as attractive model systems for studying gene function in non-vascular plants because of the relative ease of molecular manipulation by homologous recombination. Mutants affecting gametophyte development have been isolated and their analysis should provide insights into the molecular basis of gametophyte development in mosses.
Explanation:
A deeper study into the virus itself
