Cyclins
are the chemicals that regulate the cell cycle. Cyclins work by regulating the timing
of the cell cycle in eukaryotic cell. Cyclins activates cyclin dependent
kinases (CDKs) (an enzyme that works by adding <span>negatively charged phosphate groups to other
molecules in a process called phosphorylation) by binding to it to form a cyclin-Cdk
complex. This complex then functions by acting as a signal to the cell to move
to the next cell cycle phase. At the end of the event, the cyclin is degraded, Cdk
is deactivated, therefore signaling exit from a specific phase.</span>
Phase change is the change in state. i.e. water to steam or ice to water
Answer:
population - community - ecosystem - biosphere
Explanation:
<em>The correctly sorted level of organization of an ecosystem from the least inclusive to the most inclusive would be from population to community to ecosystem and finally to biosphere.</em>
A population consists of a group of organism of the same species living in a particular area at a particular time and capable of interbreeding to produce fertile progeny.
A community represents different population of organisms that are interacting with one another. Several populations make up a community.
An ecosystem consists of different communities of organisms that are interacting with themselves and the non living component of the environment.
A biosphere consists of all regions of the earth where living organisms can be found. It consists of different ecosystems that make up the earth.
<u>Hence, the population is least inclusive, followed by the community, then the ecosystem and finally the biosphere.</u>
Answer: The correct statements are 1 and 2:
1.Self-pollination occurs when the pollen from the anther is deposited on the stigma of the same flower, or another flower on the same plant.
2.Cross-pollination is the transfer of pollen from the anther of one flower to the stigma of another flower on a different individual of the same species.
Explanation:
Pollination is the transfer of pollen grains from an anthers to a receptive stigma. In most species of flowering plants, external agents bring about pollination. Also, flowers have evolved special structures and mechanisms to ensure successful pollination.
There are two types of pollination
--> Self pollination: This takes place when mature pollen grains from the anther of a flower fall on the stigma of the same flower or that of another flower on the same plant. This type of pollination brings the male gametes and egg cells of the same plant together. The resultant offspring show very little genetic variation.
--> Cross pollination: This occurs when mature pollen grains of a flower are transferred to the stigma of a flower of another plant of the same or closely related species. This brings the male gametes and egg cells of two different parent plants together. Therefore, there is greater genetic variation among the offspring.
The correct answer would be option A. Leafy gametophytes. The feature that differentiates mosses from liverworts and hornworts are the leafy gametophytes. A gametophyte is a multicellular haploid generation which is involved in the process of alternation of genes along with a diploid generation called as sporophyte.
