Out of the following given choices
a) Brooke’s finger accidentally grazes the hot
iron; she immediately yanks her hand away.
<span>
b) After a satisfying evening meal, Callum
relaxes in front of the television.
<span>
<span>c) Walking toward her car is a deserted parking
garage one night, Danica is surprised by a strange man appearing from nowhere.</span>
<span>
<span>d) Emmeline feels queasy as she approaches the
front of the class to give a speech; suddenly, her throat goes dry.</span>
<span>
The answer is B. The
parasympathetic nervous system is part of the autonomic nervous system that
regulates the unconscious actions of the body. The system is regarded as significant in the ‘rest-and-digest’
activity and also the ‘breed-and-feed’. </span></span></span></span>
1. In the heart, an action potential originates in the (E) sinoatrial node.
The cardiac action potential is a term referring to the change in the membrane potential of heart cells causing the heart to contract. Cardiac action potentials are created by a group of specialized cells capable of generating automatic action potentials and are located in the right atrium of the heart. These cells are called sinoatrial node and sometimes are referred to as the natural pacemaker of the heart. This characterization originates from the fact that sinoatrial node continuously provides action potential and sets the rhythm of the heart function.
2. The sequence of travel by an action potential through the heart is (A) sinoatrial node, atrioventricular node, atrioventricular bundle, bundle branches, Purkinje fibers.
As explained above, the cardiac action potential originates from the sinoatrial node. This action potential then travels through the atrioventricular node, which belongs to the electrical conduction system of the heart and is located between the atria and the ventricles. It is responsible for the electrical connection between the right atrium and the right ventricle. The action potential then travels to the atrioventricular bundle (or bundle of His), another part of the electrical conduction system of the heart. The atrioventricular bundle transmits the electrical impulses from the atrioventricular node to the bundle branches. The bundle branches then send the signal to the Purkinje fibers which send the electrical impulses to the ventricles, causing them to contract.
3. The correct answer is A.
The generation of an action potential in the sinoatrial node causes the contraction of the atria. When the action potential passes from the sinoatrial node to the atrioventricular node, it slows down. This causes the transport of the electrical impulse from the atria to the ventricles to slow down. This delay enables the blood (from the contraction of the atria) to fill the ventricles before their contraction.
4. This statement is true.
The interventricular septum is a structure which divides the two ventricles of the heart and it is composed of two branches, the left bundle and the right bundle branch. When the action potential reaches the interventricular septum, it then travels to the apex of the heart from where it travels upwards along the walls of the ventricles and the ventricular contraction begins.
5. This statement is true.
The bundle branches gradually become Purkinje fibers located in the interior of the ventricular walls. Purkinje fibers are specialized cells and are responsible for conducting cardiac action potentials from the bundle branches to the ventricular walls. This signal transduction causes the muscle of the ventricular walls to contract.
Answer:
12 : 3 : 1
white : yellow : green
Explanation:
Given that genes A and B control the fruit colour in following ways:
A_B_ or A_bb = white
aaB_ = yellow
aabb = green
The genes undergo independent assortment so:
AaBb X AaBb =
A_B_ : A_bb : aaB_ : aabb
9 : 3 : 3 : 1
white : white : yellow: green
12 : 3 : 1
Hence, ratio of white : yellow : green is 12: 3: 1
<span>A) bacteria. Membrane-bound organelles are found in eukaryotic cells. However, bacteria are prokaryotic, meaning that they do not have membrane bound organelles.</span>
Answer:
B. Sea levels will rise , causing floods
