Velocity = frequency x wavelength
Wavelength = velocity / frequency
= 260 / 95
= 2.736 m
= 3 m
Answer:
The options
a. sympatric speciation; vicariance
b. allopatric speciation; vicariance
c. sympatric speciation; dispersal
d. allopatric speciation; dispersal
The CORRECT ANSWER IS d.
d. allopatric speciation; dispersal
Explanation:
Allopatric speciation takes place either via dispersal, when some members of a species shifts it's habitat to a separate geographical area which leads to differentiation of the initial group into separate diverse varieties or species(as in our case study).
Allopatric speciation through dispersal could results in multiple speciation leading to an individual original species producing diverse new species; this occurrence is called adaptive radiation.
In some scenario, a population of an individual species disperses all over a region with each locating a separate niche or isolated habitat. In the course of time, the diverse demands of their just formed lifestyles causes multiple speciation events that comes from a singular species.
Answer:
- Duplex RNA (dsRNA) can suppress the expression of a gene.
- miRNAs are short, single strands approximately 21 nucleotides long.
- miRNAs suppress gene expression by interfering with transcription.
- RNA interference can temporarily suppress the expression of a target gene.
Explanation:
The RNA interference (RNAi) mechanism is a naturally occurring biological process by which an organism suppresses gene expression by using sequence-specific small non-coding RNAs that are complementary to RNA (posttranscriptional silencing) or DNA (transcriptional silencing) sequences. Since its discovery, this mechanism has been exploited in molecular biology to control the expression of target genes. There are different classes of non-coding RNAs which are able to trigger RNAi gene silencing: microRNAs (miRNAs), small interfering RNAs (siRNAs), piwi-interacting RNAs (piRNAs, only present in animals), etc. During their functioning, these non-coding RNAs are loaded into the RNA-induced silencing complex (RISC) to direct them to target sequences and trigger RNAi (for example, by cleaving target mRNAs). miRNAs are short, evolutionary conserved RNAs, that associate to the RISC complex in order to trigger both transcriptional and posttranscriptional gene silencing. During their biogenesis, small non-coding RNAs are double-stranded RNA (dsRNA), but they lose a strand (the passenger strand) when associate with the RISC complex, conserving only one strand (the guide strand) that bind by complementary base pairing to target sequences (either DNA in the nucleus or RNA in the cytoplasm).
the flowers are generally so beautiful and attractive to attract birds and insects for helping the plant to reproduce. when the bird or insect lands on some other flower, some of the pollen spreads and pollination occurs.
