Following gastrulation, the next major development in the embryo is neurulation, which occurs during weeks three and four after fertilization. This is a process in which the embryo develops structures that will eventually become the nervous system
Answer:
Watson and Crick proposed the double helical model of DNA.
Explanation:
- This model says that DNA exist as double helix. It has two polynucelotide strands running in opposite direction i.e the strands are anti-parallel.
- Each polynucleotide strand is made up of several nucleotide liknked together by phophodiester bonds.
- The two strands are not coiled upon each other but the double strand is coiled upon itself around a common axis like the spiral stair case. Here base pairs forms the stairs and backbone of two strands form railing. Back bone contains sugar and phosphate.
- The base pairing is specific, adenine always pairs with thymine and guanine always pairs with cytosine. Thus if we see any base pair, it consists of one purine and one pyrimidine.
- The two strands of DNA thus show complementary base pairing.
- The strands are held together because of hydrogen bonding between the bases in opposite strand.
- One full helical turn involves ten base pairs and the base pairs are stacked 3.4 A apart.
- This form is called as B-form of DNA.
Answer:
Naturally: only during daylight hours
Artificially: all 24 hours (under perfect circumstances)
Explanation:
Photosynthesis can only occur when a plant receives energy from a light source. Naturally, the light source would be the sun which is only around for a certain amount of hours. If the plant is under an artificial light source, like a lamp, then photosynthesis can occur at all hours of the day.
In the mid-1800s, an Austrian monk named Gregor Mendel Opens in modal popup window began his own experiments with plants. Unlike his predecessors, he used rigorous scientific methods in his experiments.
Mendel conducted his experiments with pea plants, which he grew in the garden of his monastery. The plants are easy to grow, reproduce quickly, and have several distinct characteristics Opens in modal popup window , or features, that are easy to observe. Characteristics of pea plants include flower color, seed color, and pea pod shape.
<span>Moreover, Mendel knew that each characteristic exists as one of two traits Opens in modal popup window , or forms of the character. For example, the seed color characteristic exists as one of two traits: green or yellow.</span>
Answer:
Diamond is a solid form of the element carbon with its atoms arranged in a crystal structuctre. It is formed in the mantle and delivered to the surface by deep source volcanic eruption.
Explanation:
it have exquisite beauty, inner fire, and unique physical quantity have made them so precious.
