Fertilization. Egg and sperm cells have just 23 chromosomes each. That's half as many chromosomes as regular cells. Through the process of fertilization, egg and sperm join to make a cell with 46 chromosomes (23 pairs), called a zygote.
The answer is : crossing over can increase genetic variations during meiosis
You would be referring to the <em>plant </em>cell.
Answer:
Chloroplasts may be seen on all six sides of a plant cell, which is a three-dimensional entity with typically moderately rounded corners (not in the centre because a big central vacuole fills a very large part of the volume). Chloroplasts are constantly being rearranged by the cell since they are not set in place. Chloroplasts are typically located close to so-called periclinal cell walls, which are oriented in the same 2D orientation as the leaf surface under low light. Chloroplasts seem to "escape" to the anticlinal walls in bright light. Better light harvesting in low light by exposing every chloroplast to light and photoprotection by mutual shading in strong light are likely the fitness benefits provided by this behavior. In the dark, chloroplasts also gravitate toward the anticlinal walls. Thin leaves of submerged aquatic plants like Elodea can be used as microscope specimens to observe chloroplast motions. One can gauge how much light gets through a leaf in land plants. What I just said concerning the top layer(s) of leaves' "palisade parenchyma cells" is accurate. Most of the chloroplasts are found in these cells. Numerous cells in the spongy parenchyma under the palisade layer lack well marked peri and anticlinal walls.
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How did plant cells incorporate chloroplasts in their DNA?</h2>
Chloroplasts must reproduce in a manner akin to that of some bacterial species, in which the chloroplast DNA is duplicated first, followed by binary fission of the organelle (a kind of protein band that constricts so that two daughter organelles bud off). As a result of some chloroplast DNA actually being integrated into the plant genome (a process known as endosymbiotic gene transfer), it is now controlled in the nucleus of the plant cell itself.
