Explanation:
B) False
Multiple mutations in several protooncogenes and tumor suppressor genes are required to form cancer
Cancer-causing genes, or oncogenes, develop from protooncogenes which regulate normal cell division. They may undergo mutations that alter gene expression, disrupt cell regulation and lead to the transformation of normal cells into tumor cells- their resulting proteins are abnormal or not formed. Tumor suppressor genes, which can halt unregulated cell growth and division, may also become mutated.
Each individual inherits 2 copies of a gene from their parents- a single mutation in one of these does not directly lead to cancer. Multiple activated oncogenes, in turn produce damaged, non functional proteins and together contribute to forming cancers.
Further Explanation:
During the process of cell division, spontaneous changes within the genome can arise. These mutations are errors occur when copies of the DNA within the cell are made; mutations may range from small changes called single nucleotide polymorphisms, to large scale deletions, and additions which span multiple genes. There are two types:
- somatic: these only occur within certain cells, and arise from environmental factors such as UV light
- hereditary: occur within germ cells of the parent and later the fertilized egg which forms a zygote; these are present within all cells of the new organism.
Sequences of DNA make up genes which can have different forms called alleles. DNA, which makes up the genotype, is transcribed into mRNA and later translated into amino acids which are linked together by rRNA to form proteins which make up the phenotype of an organism. Mutations in DNA sequences affect the corresponding mRNA and thus the protein encoded.
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Answer: Homologous chromosomes are randomly distributed to daughter cells, this means different chromosomes segregate independently of each other. And they exchange segments of DNA during crossing over. This recombination creates genetic diversity because genes from each parent are exchanged.
Explanation:
Meiosis is a type of cell division that produces gamete cells, which are sex cells (egg and sperm)
Chromosomes that form a pair and are found together are called homologous chromosomes, and they are inherited from each parent. During prophase of meiosis I, the homologous chromosomes exchange segments of DNA in a process called crossing over. This recombination creates genetic diversity because genes from each parent are exchanged. <u>It results in new combinations of genes on each chromosome.</u>
After that, during the anaphase of meiosis I, the two chromosomes line up on the equatorial plane of the cell. Then, they are separated and each will go to a new daughter cell. So homologous chromosomes are randomly distributed to daughter cells, <u>this means different chromosomes segregate independently of each other.</u>
1.each of several hierarchical levels in an ecosystem, comprising organisms that share the same function in the food chain and the same nutritional relationship to the primary sources of energy.
A scavenger is an organism that mostly consumes decaying biomass, such as meat or rotting plant material. Many scavengers are a type of carnivore, which is an organism that eats meat. While most carnivores hunt and kill their prey, scavengers usually consume animals that have either died of natural causes or been killed by another carnivore.
Scavengers are a part of the food web, a description of which organisms eat which other organisms in the wild. Organisms in the food web are grouped into trophic, or nutritional, levels. There are three trophic levels. Autotrophs, organisms that produce their own food, are the first trophic level. These include plants and algae. Herbivores, or organisms that consume plants and other autotrophs, are the second trophic level. Scavengers, other carnivores, and omnivores, organisms that consume both plants and animals, are the third trophic level.
Nitrogen is converted from atmospheric nitrogen (N2) into usable forms, such as NO2-, in a process known as fixation. The majority of nitrogen is fixed by bacteria, most of which are symbiotic with plants. Recently fixed ammonia is then converted to biologically useful forms by specialized bacteria.
Answer:
Figure 19.2. The Light Reactions of Photosynthesis. Light is absorbed and the energy is used to drive electrons from water to generate NADPH and to drive protons across a membrane. These protons return through ATP synthase to make ATP.
Explanation:
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