Answer:
Crossing over is the process of interchange of genetic information among non-sister chromatids of homologous chromosome pairs during meiosis (specifically during synapsis in prophase I). During this process, the synaptonemal complex enables the interchange of chromosome fragments between non-sister chromatids through crossing over. Moreover, in sexual reproduction, the zygote diploid cell can be generated by the random joining of fully differentiated haploid gametic cells (male and female gametes). The combination of random joining with the phenomenon of crossing over is known to considerably increase the genetic variation of the resulting offspring. After zygote formation, the successive cycles of cell divisions during embryonic development will develop an organism that during its adult stage will reproduce via sexual reproduction.
What are some changes that can occur in ecosystems?
Answer:
There are so many changes that occur in ecosystem, they are:Habitat change. climate change. invasive species. over exploration. pollution.Explanation:
Hope it helps you.Seasons, tide cycles, population sizes, landscape changes, succession evolution, and climate change are instances of changes that can occur in ecosystems.
What is an ecosystem?An ecosystem is a geographical area wherein plants, animals, and other organisms, along with weather and landscape, coexist to form a life bubble.
The instances of changes that can occur in ecosystems can be seasons, tide cycles, population sizes, landscape changes, succession evolution, and climate change.
Thus, these are some changes that can occur in the ecosystem.
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The spread of cancer cells from one site to others in the body is known as _____.
Answer:
metastasis
Explanation:
Metastasis is the process in which cancer cells break away from the place where they first formed and travel through the bloodstream to other parts of the body where they form a new tumor.
Hope that helps.
You are a graduate student in the lab of a famous fly geneticist. You need to analyze a batch of mutant flies that were recently created in her laboratory to identify the single gene that is most likely mutated in each of the flies. Drag the mutations on the left to the appropriate blanks on the right to complete the sentences.
a. knirps (a gap gene)
b. hunchback (a gap gene)
c. hedgehog (a segment-polarity gene)
d. wingless (a segment-polarity gene)
e. kruppel (a gap gene)
f. even-skipped (a pair-rule gene)
1. Mutant fly F has predominantly lost abdominal structures, which is likely the result of a mutation in_____.
2. The wings are missing in mutant fly L, which is likely the result of a mutation in______.
3. Thoracic and abdominal structures are missing in mutant fly Q. The gene most likely responsible for this mutation is______.
4. Segment-sized sections of every other segment are missing in mutant fly Z. One likely candidate gene is_______.
5. Mutant fly X has lost the head and thorax. The gene most likely responsible for this mutation is_______.
6. The mutation observed in mutant fly O resulted in defects within the anterior or posterior regions of each segment. The gene that most likely caused this mutation is_______.
Answer:
knirps (a gap gene)
wingless (a segment-polarity gene)
kruppel (a gap gene)
even-skipped ( a pair-rule gene)
hunchback (a gap gene)
hedgehog (a segment-polarity gene)
Explanation:
The gap, segment-polarity and pair-rule genes play central roles in controlling embryonic development of arthropods. In the first place, the gap genes are associated with the formation of contiguous body segments, thereby mutations in these genes result in gaps in the normal body plan of the embryo. For example, in Drosophila melanogaster, mutations in the knirps, Krüppel and hunchback genes result in deletion of body segments. These genes are also known to regulate segment polarity genes, which determine the polarity of the embryonic parasegments by modulating Wnt and Hedgehog signaling pathways. Finally, the pair-rule genes work together with gap genes to control embryonic development of alternating body segments.