Specialized tissue on the wall between the atria. Electrical impulses pass from the pacemaker (SA node) through the _______ and the atrioventricular bundle (bundle of His) toward the ventricles.atrium (pl. atria)One of two upper chambers of the heart.capillary<span>Smallest blood vessel. Materials pass to and from the bloodstream through the thin walls. They have walls that are only one endothelial cell in thickness. This delicate, microscopic vessel carries nutrient-rich, oxygenated blood from the arteries and arterioles to the body cells. There, the nutrients are burned in the presence of oxygen (catabolism) to release energy.
At the same time, waste products such as carbon dioxide and water pass out of the cells and into these blood vessels. Waste-filled blood then flows back to the heart in small venues, which combine to form larger vessels called veins.</span>carbon dioxideGas (waste) released by body cells, transported via veins to the heart, and then to the lungs for exhalation.coronary arteriesBlood vessels that branch from the aorta and carry oxygen-rich blood to the heart muscle.deoxygenated bloodBlood that is oxygen-poor.diastole<span>Relaxation phase of the heartbeat.</span>
        
             
        
        
        
<u>Answer</u>:- Active transport 
<u>Explanation</u>:-
There are two types of membrane transports
1. Passive transport - this type of transport occurs without the input of any energy and the molecules move along the concentration gradients that is from <em>high concetration to low concentration.</em>
2. Active transport- this type of transport takes place to move the molecules against the concentration gradient that is from <em>low concentration to high concentration.</em>
<em>The active transport is of two types:</em>
1. <em>Primary active transport-</em> in this type of transport <em>ATP</em> is used as an energy source to move the substances against the concentration gradient.
2.<em>Secondary active transport</em> - in this type of transport the gradient formed by the active transport is utilized and it involves the movement of 2 substances at a time aross the membrane. That is the movement of one molecule is coupled to another.
- The membrane proteins that are associated with active transport are called as <em>carrier proteins</em>. These proteins have a binding site for the molecules that they transport. Once they bind to the specific molecules, a conformation change is induced and this leads to the transport of the molecule across the membrane.
So, the <em>active transport is basically responsible for utilizing the energy from ATP and carrier proteins to move the substances across the membrane against their concentration gradient i.e. from low concentration to high concentration.</em>
 
        
             
        
        
        
The terms dominant and recessive describe the inheritance patterns of certain traits. ... For a recessive allele to produce a recessive phenotype, the individual must have two copies, one from each parent. An individual with one dominant and one recessive allele for a gene will have the dominant phenotype. 
Hope this helpsss:))))