Answer:
Underground stem, Aerial stem, and subaerial stem.
Explanation:
Plant stems can be Underground stem, Aerial stem, and subaerial stem due to its presence and strength of the stem. Underground stem are thick stems that run below the ground surface. e.g rhizome. Aerial stems are thin stems that can not stand erect. Examples include watermelon and strawberry etc. Subaerial stems are very thin stems that do not rise up but grow just above the ground. for example, water plantain, flowering rush etc.
Asexual <span> most of these are also capable of </span>sexual <span>reproduction</span>
Answer:
Crossing over
Explanation:
Crossing over is the process during which two chromatids of two homologous chromosomes exchange part of their genetic segments. It occurs during the pachytene stage of prophase I of meiosis I.
Linked genes are mostly inherited together and do not exhibit independent assortment. However, when linked genes are present far apart from each other on the same chromosome, crossing over can occur between them to produce recombinant chromatids. Therefore, crossing over can break the linkage and produce recombinant progeny as it occurs during the independent assortment of unlinked genes.
These genes could have arisen by gene duplication.
<h3>What is gene duplication?</h3>
Gene duplication is the process of copying a section of DNA that codes for a gene. A retro transposition event or a recombination mistake are both potential causes of gene duplication. As a result, the duplicate gene coding may experience a significant number of modifications throughout time. This might prevent the gene from functioning or, in other situations, give the creature a benefit.
Gene duplication is a phenomenon that can happen through a variety of ways:
- Ectopic Recombination: Uneven crossing-over between misaligned homologous chromosomes during meiosis might result in duplications. A duplication at the exchange site and a reciprocal deletion are the results of this recombination.
- Replication Slippage: Short genomic sequences can be duplicated as a result of the replication error known as replication slippage. DNA polymerase starts copying the DNA during replication, but eventually the polymerase separates from the DNA, causing replication to stall. The replicating strand is incorrectly aligned when the polymerase reattaches to the DNA strand, which accidentally results in several copies of the same portion.
- Aneuploidy: When a single chromosome's nondisjunction causes an abnormally high number of chromosomes, this condition is known as aneuploidy. Aneuploidy is frequently damaging and frequently causes spontaneous miscarriages in mammals. Some aneuploid people can survive. For instance, human trisomy 21 causes Down syndrome but is not lethal.
Learn more about gene duplication here:
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Answer:
promote stomatal closure during drought stress.
Explanation:
Abscisic acid inhibits the growth and stomatal opening, specifically when the plants are exposed to some stress conditions. Abscisic acid also regulates the seed maturation and seed dormancy. ABA concentration in leaves increases multiple folds under drought conditions. Its accumulation in leaves promotes closure of stomata and prevents the water loss by transpiration. ABA is required to restore the turgor pressure under drought conditions by stimulation of stomatal closure.
