Answer:
D. Fibrocartilage
Explanation:
In order to understand the question, we need to review the structure of intervertebral discs.
Intervertebral discs consist of two parts:
It forms the central part of the intervertebral disc and consists of mucoid substance.
It is composed of encircling layers of fibrocartilage and fibrous tissue surrounding the nucleus pulposus
<u>SLIPPED DISC:</u>
It is characterized by the protrusion of nucleus pulposus through the annulus fibrosus accompanied by the compression of spinal nerves.
Patient may present with loss of sensory sensations or pain or both.
<u>CORRECT ANSWER:</u>
From the above review, the correct answer is <u>D. fibrocartilage</u> as it forms the annulus fibrosus.
The main responsible for the delay among the atrial and
ventricular contractions is the action potential conduction velocity of the AV
node cells. If the atria and ventricles contract simultaneously, atria cannot
give any help in filling the ventricles, which is needed, especially in those
with stiff ventricles as in the elderly. Hence atria have to contract first and
then the ventricles.
If you compare the original DNA with the mutated DNA, the first C got “substituted” by an A after the mutation.
So the answer is (C) substitution.
Answer:
A. 3
B. 4
C. 5
D. 6
E. 2
F. 1
Explanation:
1. Integumentary system.
This is an organ system that consists of hair, skin, nails and exocrine glands with receptors that senses the outer stimulus and environmental conditions, through homeostasis maintain stability of the internal environment.
2. Nervous system.
It receives sensory information and signals, convert them to nerve impulses that are transmitted to the body and brain via the spinal cord using nuerons and axons. It also intergrates, retains and analyses information in the brain.
3.Endocrine system.
Secretes hormones and chemicals in response to stimulus from the nervous system to maintain balance using feedback loops i.e, negative and positive.
4. Lymphatic system.
Part of the immune system that consist of vessels that carries lymph, cleaning the blood by filtering lymph with foreign particles into the lymph node.
5. Urinary system.
Used to eliminate waste from the body, regulates blood pressure, volume and pH. It also used to retain electrolytes and metabolites.
6. Respiratory system.
Used for gaseous exchange using the blood, heart and lungs. Air enters the lungs, transported by blood and is pumped by the heart to all body parts where oxygen is dropped, carbon dioxide is collected by the veins to the lungs and released to the atmosphere.
Answer:
1. Stabilizing Selection
2. Directional Selection
3. Disruptive Selection
Explanation:
Stabilizing Selection
This type of natural selection occurs when there are selective pressures working against two extremes of a trait and therefore the intermediate or “middle” trait is selected for. If we look at a distribution of traits in the population, it is noticeable that a standard distribution is followed:
Example: For a plant, the plants that are very tall are exposed to more wind and are at risk of being blown over. The plants that are very short fail to get enough sunlight to prosper. Therefore, the plants that are a middle height between the two get both enough sunlight and protection from the wind.
Directional Selection
This type of natural selection occurs when selective pressures are working in favour of one extreme of a trait. Therefore when looking at a distribution of traits in a population, a graph tends to lean more to one side:
Example: Giraffes with the longest necks are able to reach more leaves to each. Selective pressures will work in the advantage of the longer neck giraffes and therefore the distribution of the trait within the population will shift towards the longer neck trait.
Disruptive Selection
This type of natural selection occurs when selective pressures are working in favour of the two extremes and against the intermediate trait. This type of selection is not as common. When looking at a trait distribution, there are two higher peaks on both ends with a minimum in the middle as such:
Example: An area that has black, white and grey bunnies contains both black and white rocks. Both the traits for white and black will be favored by natural selection since they both prove useful for camouflage. The intermediate trait of grey does not prove as useful and therefore selective pressures act against the trait.
