The randomness in the alignment of recombined chromosomes at the metaphase plate, coupled with the crossing over events between nonsister chromatids, are responsible for much of the genetic variation in the offspring. To clarify this further, remember that the homologous chromosomes of a sexually reproducing organism are originally inherited as two separate sets, one from each parent. Using humans as an example, one set of 23 chromosomes is present in the egg donated by the mother. The father provides the other set of 23 chromosomes in the sperm that fertilizes the egg. Every cell of the multicellular offspring has copies of the original two sets of homologous chromosomes. In prophase I of meiosis, the homologous chromosomes form the tetrads. In metaphase I, these pairs line up at the midway point between the two poles of the cell to form the metaphase plate. Because there is an equal chance that a microtubule fiber will encounter a maternally or paternally inherited chromosome, the arrangement of the tetrads at the metaphase plate is random. Thus, any maternally inherited chromosome may face either pole. Likewise, any paternally inherited chromosome may also face either pole. The orientation of each tetrad is independent of the orientation of the other 22 tetrads.
Explanation:
Answer:
Answer is option D.
Flowers contain parts for making seeds.
Explanation:
The part of the plant that is responsible for the sexual reproduction in plants is known as flowers. A flower is said to be complete if contains sepals, petals, stamens and pistil. If the flower lacks one or more structures, it is an incomplete flower.
A complete flower consists of a vegetative part and a reproductive part. The vegetative part contains petals (a bright coloured structure that attracts insects and birds) and sepals (a green coloured structure that protects rising buds and is usually found beneath the petals). The reproductive parts include stamen or androecium (male reproductive organ) and pistil (female reproductive organ). A flower may consists of only female parts or only male parts, or both.
Stamen contains two parts - anther, which produce and store the pollens (male gametes) and filament, which support the anther. Pistil contains three parts - stigma, which receives the pollen grains and style that connects stigma and the ovary, and ovary which contains a lot of ovules (female gametes) which forms the seed.
Flowers reproduce by pollination, a process in which the pollen are transferred to the stigma of another flower. A pollen tube emerges from the pollen grain and grows through the style and reaches an ovule inside the ovary. Then the nucleus of the pollen grain passes through the pollen tube and fuses with the nucleus of the ovule and this process is known as fertilisation. The fertilised ovules become seeds and the ovary transforms into the fruit. The seeds are dispersed through various methods and the embryo inside them will grow into adult plants.
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Answer:</h2>
The security mirror is a <u>convex mirror</u>.
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Explanation:</h2>
A convex mirror is a round reflecting surface in which its protruding side faces the wellspring of light. Vehicle manufactures frequently consider fish eyes reflect while different material science writings allude to it as a security mirror.
When a direct light emission is passed on the convex mirror, the mirror will permit the first parallel beams that make up the bar to wander in the wake of striking the intelligent surface.
Since, they have more extensive fields of view than other intelligent surfaces, for example, plane mirrors or inward mirrors, they are usually utilized in vehicle side mirrors.
Explanation:
Biodiversity refers to the diversity of biology or living organisms on Earth. The biodiversity is responsible for maintaining various biogeochemical on this planet.
The biodiversity has been drastically affected by the anthropogenic factors which has caused the deterioration of biodiversity.
The main anthropogenic factors are:
1. Habitat fragmentation: the human activities like construction of road passing through the habitat for organisms can lead to habitat fragmentation which could decrease the gene flow in the species.
2. Deforestation: the cutting of trees has led to the extinction of species.
3. Climate change : Global warming is the result of the industrial revolution initiated by humans in 19th century.
4. Exploitation of natural resources: the humans have continuously exploited human resources for their use.
5. Hunting of animals: The hunting of animals is one of the major factor for extinction of animals.
