Answer:
Option A, Start the reaction by absorbing light energy
Explanation:
Chlorophyll is a green color pigment in plant that helps in entrapping sunlight. Being green in color, it absorbs the blue and red light and reflects the green light. The molecules of chlorophyll gains energy from sunlight and then jumps to higher energy levels by the process known as photo excitation. These excited molecules get ionized to further initiate the process of photosynthesis.
Hence, option A is correct.
Answer:
Natural selection is generally limited to modifying structures that were present in previous generations and in previous species
Explanation:
The basic idea of biological evolution is that populations and species of organisms change over time. Today, when we think of evolution, we are likely to link this idea with one specific person: the British naturalist Charles Darwin.
In the 1850s, Darwin wrote an influential and controversial book called On the Origin of Species. In it, he proposed that species evolve (or, as he put it, undergo "descent with modification"), and that all living things can trace their descent to a common ancestor.
Natural selection, genetic drift, and gene flow are the mechanisms that cause changes in allele frequencies over time. When one or more of these forces are acting in a population, the population violates the Hardy-Weinberg assumptions, and evolution occurs. The Hardy-Weinberg Theorem thus provides a null model for the study of evolution, and the focus of population genetics is to understand the consequences of violating these assumptions.
New gene variants (i.e., alleles) are produced by random mutation, and over the course of many generations, natural selection may favor advantageous variants, causing them to become more common in the population.
THE ELECTRON TRANSPORT CHAIN is responsible for releasing energy that is used to pump hydrogen ion. The energy which is released in form of electrons are passed through the electron transport chain and used to pump protons into the thylakoid compartment of the plant cell.
Answer:
Explanation:
1. can generate energy – Both , In landfills methane gas is produced which is used to generate electricity, like wise heat energy produced in incinerator is also used for producing energy
2. emits toxins through combustion – Incinerators produce dioxins which is a dangerous chemical
3. drains liquids into the ground – Land fill, leachate is a common issue with all landfill site.
4. releases greenhouse gases – Both, methane and other carbon gases are produced in both landfill and incinerators
5. requires a substantial amount of land – land fill site , needs a large land to dump the city waste
6. generate ash – Incenerator only
Answer:
The miRNAs act as post-transcriptional silencers, as they are similar to specific mRNAs and regulate their stability and translation. They are small endogenous non-coding ribonucleic acid (RNA) molecules, with about 22 nucleotides, which act as regulators of gene expression in plants and animals, at the post-transcriptional level through the cleavage of a target messenger RNA (mRNA) or repression of translation.
In general, most miRNA genes are transcribed by RNA polymerase II in the nucleus in primary miRNAs (pri-miRNAs). Individually, a pri-miRNA can produce a single miRNA or contain groups of two or more miRNAs that are processed from a common primary transcript. These long pri-miRNA are cleaved by a complex comprising the double-stranded RNAse III enzyme (DROSHA) and its essential cofactor, the binding protein DGCR8 (DiGeorge Syndrome Critical Region 8 protein) in mammals. DROSHA contains two domains of RNAse III, each of which cleaves a strand of the RNA resulting in the precursor microRNA (pre-miRNA) with about 70 base pairs, which contains a double-stranded stretch and a single-stranded loop, forming a structure in clamp. The pre-miRNA is exported to the cytoplasm by the protein exportin-5 (XPO-5), where it is cleaved by DICER1, an RNAse III that assesses the 3 'and 5' ends of the pre-miRNA, generating a mature miRNA with about 22 nucleotides. The processing of pre-miRNA by Dicer promotes the unfolding of the RNA duplex in the form of a clamp. The position in the formation of the clamp can also influence the choice of tape.
Explanation:
