There are a number of amino acids that have formed under certain environmental conditions if the required elements are present and the energy conditions ar compatible with chemical assembly. These conditions have also allegedly formed amino acids on meteors, asteroids and comets.
But, amino acids are a very minor component of more complex biochemical assemblies required for life. Pentose sugars are also required, which form under different environmental conditions than amino acids. More importantly, only left-handed homochiral amino acids and right-handed homochiral sugars can form functioning biochemical assemblies that are viable in an organism. But, natural conditions, like hydrothermal vents only produce racemic versions of sugars and acids, meaning they are always approx. 50% left and right handed. This is fatal to forming viable biochemical assemblies.
Further, it is not possible for all of the 20+ homochiral amino acids needed for a living organism to form naturally. The only ones found have been the simpler amino acids. Also, the 4 critical nucleotide amino acids, C, G, A, T, do not form naturally, are not homochiral, nor in the right proportions.
The geo/hydrothermal vent conjecture is nonsensical. These are open systems, susceptible to currents, mineral contamination, salinity, ph, and temperature, making them a totally unacceptable environment for the precise and exact placement of elements to assemble to form life.
Answer:
lignified vascular tissue
Explanation:
Stems of Vascular plants are made of vascular tissues and lignin which gives it is characteristics stiffness and the ability to grow tall to access more light and air.
Answer:
A glance of earth taken from space will depict it blue. This blue colour is actually water, the major part of the earth is covered with water. We need water for almost everything, for example- drinking, bathing, cooking etc and therefore we should know about the properties of water. 65 % human body is composed of water. Water is essential for the survival of life on earth. Water is distributed unevenly on the earth’s surface. It forms a major solvent and dissolves almost every polar solute. So let us have a look at its properties.
Physical properties of water : Water is a colourless and tasteless liquid. The molecules of water have extensive hydrogen bonds resulting in unusual properties in the condensed form. This also leads to high melting and boiling points. As compared to other liquids, water has a higher specific heat, thermal conductivity, surface tension, dipole moment etc. These properties form the reason for its significance in the biosphere. Water is an excellent solvent and therefore it helps in the transportation of ions and molecules required for metabolism. It has a high latent heat of vaporization which helps in the regulation of body temperature
Chemical properties of water: Amphoteric nature:
Water can act as both acid and base, which means that it is amphoteric in nature.
Example:
Acidic Behaviour: H2O(l)+NH3(aq) ⇌ H3O+(aq)+NH+4(aq)
Basic Behavior: H2O(l)+H2S(aq) ⇌ H3O+(aq)+HS−(aq)
Redox reactions:
Electropositive elements reduce water to hydrogen molecule. Thus water is a great source of hydrogen. Let us see an example in this case:
2H2O(l)+2Na(s)→2NaOH(aq)+H2(g)
During the process of photosynthesis, water is oxidized to O2. As water can be oxidized and reduced, it is very useful in redox reactions.
Hydrolysis reaction
Water has a very strong hydrating tendency due to its dielectric constant. It dissolves many ionic compounds. Some covalent and ionic compounds can be hydrolyzed in water.
Explanation:
