The last universal common ancestor (LUCA) is the most recent organism from which all organisms on Earth descended. While it is challenging to definitively determine the specific characteristics of LUCA, scientists have proposed certain properties that it likely possessed based on evolutionary and genetic evidence. Let's analyze each property mentioned in the question:
1. Simple cellular structure:
- LUCA is believed to have had a simple cellular structure. This means it likely had basic cellular components, such as a cell membrane, cytoplasm, and possibly some form of genetic material.
2. Anaerobic metabolism:
- LUCA is thought to have relied on anaerobic metabolism, which means it obtained energy from sources other than oxygen. This is because molecular oxygen was not abundant in the early Earth's atmosphere when LUCA is believed to have existed.
3. Prokaryotic cell type:
- It is widely accepted that LUCA was a prokaryote, meaning it had cells lacking a nucleus or other membrane-bound organelles. Prokaryotes are considered the most ancient type of cells on Earth.
4. Extremophile characteristics:
- While it is difficult to determine the specific environmental conditions in which LUCA lived, some scientists propose that it could have been an extremophile, capable of surviving in extreme environments like high temperatures, high salinity, or acidic conditions. However, this is still a topic of scientific debate and further research is needed.
5. Heterotrophic nutritional strategy:
- LUCA is believed to have been heterotrophic, meaning it obtained nutrients by consuming organic compounds produced by other organisms. This is in contrast to autotrophs, which can produce their own food through processes like photosynthesis.
In conclusion, based on current scientific understanding, LUCA is likely to have possessed the properties of a simple cellular structure, anaerobic metabolism, prokaryotic cell type, and a heterotrophic nutritional strategy. The presence of extremophile characteristics is still a subject of ongoing research and scientific investigation.
I hope this explanation clarifies the properties that LUCA is believed to have had. Let me know if you have any further questions.
B. The period of interaction beween the Islamic and Mongol empires.
C. The period between the Greek and the Roman dominance over European culture.
D. The period following the decline of the Roman Empire in Europe.
Answer: The period following the decline of the Roman Empire in Europe.
Explanation: A p e x
Endothermic reaction
Exothermic reaction
Endothermic reaction
An endothermic reaction is those reactions that take up energy from the environment as that proceeds. The opposite is an exothermic reaction that gives off energy to the environment.
Explanation:
When cooking an egg you require energy to break down the interactions between the protein chains and atoms of the raw egg so they are rearranged into a cooked egg. This is akin to the denaturing of proteins. Cooking food helps ease their digestion. Because we need energy to break down the interactions and bonds of the proteins in the egg this is why we use fire in cooking. This is, therefore, an endothermic reaction.
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phytoremediation
herbicide tolerance
gene transfer to nontarget species
Answer:
The answer is D. Gene transfer to non-target species.
Explanation:
Using DNA technology we have made several genetically modified crops called GM crops. But sometimes the transgenic trait or gene may effect the non-target species. For example Bt-crops were found damaging the soil health. These pest resistant Bt-crops release Bt toxin near the soil root zones. High levels of Bt toxin can affect the health of soil as well as the soil insects. Hence GM crops must be monitored for the effects on non-target species.
Answer:
The correct answer is: Gene transfer to non-target species. It is believed within the scientific field that these risks directly affect environmental impacts and need to be assessed on a case by case basis and recommended post-release ecological monitoring.
Explanation:
Transgenic crops could possibly entail positive or negative indirect environmental effects through changes in agricultural practices such as pesticide and herbicide use and cropping patterns. Agriculture affects the environment it does not matter which type we are talking about. Then it is normal to conclude that the use of new genetic techniques in agriculture will also affect the environment.