To Identify Parenchyma and Sclerenchyma Tissues in Plants. ... As the cells have a thickened cell wall, little protoplasm, and no nucleus, we can confirm that the slide contains sclerenchyma tissues. To Identify Striated Muscle Fibres and Nerve Cells in Animals.
The appearance of fossils would the the answer.
Although there has been some scientific debate about what fossil strata should mark the beginning of this period, the "International Geological Congress" determined that the Cambrian period was approximately 543 million years ago of which the first appearance in the fossil record of worms that made horizontal burrows was discovered.
Answer and Explanation:
The Huntington disease is caused by a mutation in the gene that codifies for the Huntingtin protein (Htt). The mutation produces an altered form of the protein leading to the neuron´s death in certain areas of the brain.
The Huntington disease characterizes for being,
- Hereditary, passing from generation to generation. To express the disease, a person must have been born with an altered gene.
- Autosomal, affecting men and women equally, because the mutated gene is located on an autosomal chromosome.
- Dominant, which means that by getting only one copy of the altered gene coming from any of the parents, the receiving person will express the disease. The mutation in the gene dominates over the normal gene copy.
- Expressed by heterozygosis. Most people affected by the disease are heterozygous, with a normal copy and a mutated copy.
There are just a few cases all around the world (3% approximately) in which the disease is expressed with no family history. The progenitors are not affected by the mutation. These cases are very rare and are called <u>"de-novo" mutations.</u> A new mutation is spontaneously produced and it is not inherited from any of the parentals. It consists of an increase in the number of CAG repetitions. In a normal person, the number of CAG repetitions is less than 35. When there are 40 or more repetitions it occurs the disease. But when there are between 35 and 39 repetitions, the penetrance of the disease is incomplete. This is a "gray zone". Those alleles that fall in the gray zone are unstable and might produce the HD. Individuals with these unstable alleles have a tendency to increase the number of repetitions from generation to generation until the number reaches 40 repetitions and the person expresses the disease. This <u>usually occurs in the paternal germinal line</u>, as it is particularly unstable in sperm and probably meiosis greatly affects their instability, causing an increase in the number of CAG repeats.
the three kinds of nitrogenous wastes based on the energy required to synthesize them are arranged; Ammonia < urea < uric acid.
Nitrogenous wastes are the nitrogen compounds that organisms use to get rid of excess nitrogen. Ammonia, urea, and uric acid are the most common nitrogenous wastes that animals excrete. Protein metabolism generates all of these nitrogenous wastes.
Ammonia is the most toxic of these nitrogenous wastes, and it is the most common but requires the least energy. Urea is more harmful than uric acid, but it is less harmful than ammonia, reducing the amount of energy required to synthesize it. Uric acid is the least harmful, a non-poisonous particle with four nitrogen molecules. This is useful for birds and reptiles that lay hard eggs because it eliminates the most nitrogen, uses the least amount of water, and is not toxic. It also takes the most energy input.
Know more about urea here: brainly.com/question/14453829
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Genetically modified crops are genetically engineered such that a desired trait is enhanced or reproduced to appear in every offspring. Genetically engineered corn has been engineered to resist pests and herbicides; thus, we have more yield and many people especially in the low class society can afford. A disadvantage, yet is still a debate, is that genetically engineered crops such as corn, has toxic effects to internal organs such as our liver, a vital internal organ.
