Answer:
a. substantia nigra
b. substantia nigra (it is repeated)
Explanation:
Parkinson's disease is a neurodegenerative disease that is caused by the death of neurons that release the neurotransmitter dopamine in the <u>substantia nigra</u>, or locus niger, -a region of the brain that regulates brain circuits that give the 'orders' to initiate voluntary movements- .
The lack of this neurotransmitter leads to the occurrence of the main symptoms suffered by patients: decreased movements, muscle stiffness, postural instability and tremor. These failures are generated by the abnormal way in which neurons work in the absence of dopamine through a mechanism that is not known in depth.
It is the second most frequent neurodegenerative disease, after Alzheimer's disease, with a prevalence of 2% in people over 65 years. The characteristic symptoms of stiffness, bradykinesia and tremor are associated with losses of neurons in the substantia nigra and dopamine depletion in the striatum. There are large cytoplasmic inclusions, called Lewy bodies, which are the pathological mark of the disease and appear predominantly in neurons that contain melanin of the nigra substance. Genetic studies in a subgroup of families with Parkinson's disease with autosomal dominant inheritance found a locus on chromosome 4q-21 23 and a mutation in the gene that encodes a synaptic protein, α-synuclein.
Answer:
Your answer for this is D
Homeostasis can be defined as the state of maintenance of the constant internal conditions by the living organisms. The homeostasis is maintained by the body so that it may function properly. The homeostasis will be disturbed by the reduced intake of the food and water. Healthy intake of water and food is essential in maintaining the homeostasis of the body. The elevated or depressed blood pH along with extreme body temperatures will also disturb the homeostasis of the body making the person sick. Moreover, certain infectious organisms also alters the homeostasis of the body.
Hence, all the options are correct.
Primary succession would most likely occur after a lava flow.
Answer:
G and K
Explanation:
Crossing-over is a genetic phenomenon that occurs in meiosis, specifically, Prophase I. It is when chromosomal segment (genes) are exchanged between non-sister chromatids of homologous chromosomes. Crossing-over occurs only to genes that are UNLINKED i.e. genes located on different chromosomes or far apart on the same chromosome.
This unlinked genes are said to have the highest RECOMBINATION FREQUENCY. Crossing-over allows genes on the same chromosome but far apart from each other, assort independently, which allows alleles to be recombined on the same chromosome. This phenomenon does not occur to genes that are close on the same chromosome as they will be inherited together as a unit.
In this case, G and K are the farthest apart, hence, they will have the highest RECOMBINATION FREQUENCY i.e. the likelihood for homologous crossing-over to take place during meiosis.
