Answer:
c. the height of radish seedlings is measured
Explanation:
Quantitative measurements revolve around the quantity of things and exact measurements. The measured height of a radish seedling is the perfect example of that.
Memory technique:
- <u>Quantit</u>ative observations involve <u>quantit</u>y (numbers).
- <u>Qualit</u>ative observations involve <u>qualit</u>y (descriptions, features, i.e. color, smell, shape)
The cardiac notch is the concave area in the left lung that leaves a space for the heart to accomodate. The corrcet answer is <u>cardiac notch</u>.
<h3>
What is the cardiac notch?</h3>
The left lung has superior and inferior lobules, one oblique fissure, it is adjacent to the heart, the aortic arch, the thoracic aorta, and the esophagus. It also has a cardiac notch.
The cardiac notch is a concave lung area where the heart accommodates. Its main function is to leave a space for the heart to lay. It is placed in the anteroinferior border of the superior lobule of the lung.
Since the cardiac notch is the area where the heart is placed, it only appears in the left lung.
The correct answer is cardiac notch. The medial surface of the left lung has a cavity that accommodates the contents of the mediastinum. It is called the _<u> cardiac notch</u>_.
You will learn more about the lungs at
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Answer:
Once an organism is beyond a certain size, it cannot get essential molecules into and out of cells solely by diffusion. Diffusion is limited by the surface area to volume ratio of the organism.
Answer:
D. Calcium ions.
Explanation:
Here we are talking about the mechanism of muscle contraction. The most accepted theory of muscle contraction is sliding filament theory. It was given by Huxley and Huxley. During the process actin filaments slides over myosin filament by forming cross bridges. The sequence of events are as follows:
a. An action potential propagates through the motor nerve and reach the nerve endings on the muscle fiber at neuro-muscular junction.
b. Neurotransmitter called acetylcholine is released by the nerve endings.
c. Acetylcholine binds to the receptors on muscle fiber and opens the gated channels which causes flow of Na+ ions into the muscle fiber.
d. This influx of sodium ions initiates an action potential in the muscle fiber which reaches the T- tubules or transverse tubules. Here it causes the sarcoplasmic reticulum to release large amounts of calcium ion.
e. Calcium ions are responsible for initiating the attractive forces between actin and myosin filaments. Cross bridges are formed, actin slides over myosin causing the contraction of muscle.
The ability of an organism to survive and reproduce in its environment is called adaptation. Fitness is a result of adaptation.
