Answer: C. Homologous chromosomes are separated in meiosis but not in mitosis.
Explanation: There are two main types of division that take place in eukaryotic cells, mitosis, and meiosis. Mitosis is the type of division that is used for growth, repair, and replacement of tissues. Therefore it is not necessary that the cells have different chromosome numbers or are varied genetically in the daughter cells in the case of mitosis.
Meiosis is the division that takes place to form the gametes for sexual reproduction. It is important in the first stages of meiosis I, to introduce variation and to halve the chromosome number.
Chromosomes numbers are halved (from 46 to 23) during meiosis I because the gametes (sperm and egg) come together and fuse during fertilization to form a zygote. When this fusion occurs (23 from the zygote and 23 from the egg), the chromosome number needs to be returned to that of the parent cell (46).
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Genetic variation is introduced during synapsis which only occurs in meiosis, not mitosis. Homologs exchange genetic information during crossing over of synapsis. Entire chromosomes also separate during meiosis I.
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At the end of meiosis, four genetically unique cells are produced with half the number of chromosomes as the parent cell (23 cromosomes) . After the process of mitosis is completed, two cells genetically identical to each pther are produced and have the same number of chromosomes as the parent cell (46 cromosomes).
Genetic variation is actually important because of changing environmental conditions.
The carbon cycle:
The carbon cycle is the process in which carbon travels from the atmosphere into organisms and the Earth and then back into the atmosphere. Plants take carbon dioxide from the air and use it to make food. Animals then eat the food and carbon is stored in their bodies or released as CO2 through respiration.
Hope this helps :)
Answer:
There are many invasive animal sand plants which are harmful for native flora and fauna. Some of the invasive or alien species are as following:
<u>1. The Nile Perch:</u><em> </em>Nile Perch is a type of fish which is native to African lake and river systems but if it is introduced in other countries lake it can be dangerous to other fishes in that lake. It was earlier introduced to Lake Victoria but after sometime it was evaluated that native fishes got extinct and the Nile Perch become very huge in size.
<u>2. The cotton whitefly: </u> Cotton whitefly are native to India but now can be found on most of the continents and have very bad impact on the fauna or agricultural plants. They have capability of transmitting upto 100 different plant viruses. find them thriving
<u>3. The desert locust:</u> The desert locust is a species of locust which can fly and are one of the most disastrous migratory pests in the world. They feed over green green vegetation, including pasture, crops and fodder. They have very bad impact on native flora as they are migratory pests. They are found in Africa and migrated to nearby countries such as India and damages the native flora.
<u>4. European starlings:</u> European starlings are the bird species which fight with native species for food and shelter. They are found in Alaska and Mexico and proved invasive in U.S. as the number of native birds decreased with their introduction.
B. Mutations cause a person's body cells to divide uncontrollably. There isn't a signal for cells to stop dividing, so this can cause cancer because cancer cells won't stop dividing without this signal.
Answer:
Promoter.
Explanation:
It is promoter because Promoter is a DNA sequence where's the gene transcription begins. It is the
DNA sequence which RNA polymerase binds or join to
so as to begin transcriptionn of a gene . It is a region where the regulatory elements i.e protein will bind to and the Promoter sequences are found directly upstream or at the end of 5' of the transcription initiation site. This can also encode RNA such as mRNA, trans and so on.
