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alisha [4.7K]
3 years ago
13

A student conducted an experiment to determine how long it would take for Substance A to freeze. She recorded the substance’s st

ate of matter every five minutes into her data table . In this example, Substance A is a (an) ________________.
A. Control group
B. Independent (test) variable
C. Dependent (outcome) variable
D. Constant variable

Biology
1 answer:
Leona [35]3 years ago
6 0
B. Independent (test) variable
You might be interested in
Assignment: Cell Size Exploration
iris [78.8K]

Explanation:

1. As cells increase in size, their surface area:volume ratios decrease rapidly; larger cells have a harder time moving molecules across the membrane. Thus, substances required for cell growth cannot permeate the cell; cell growth is limited as the cells grow further.

2.Surface area to volume ratio is 6 units of surface: 1 unit of volume

surface area=   6cm^{2} or (1 cm x 1 cm x 6 )

volume=  1cm^{3} (1cm x 1cm x 1cm)

With a high surface area to volume ratio, substances readily diffuse across the membrane of the cell, into the cytoplasm. The cell is able to obtain all the materials it requires.

3. Surface area to volume ratio is 3 units of surface: 1 unit of volume

surface area=   3cm^{2} or (1 cm x 1 cm x 3 )

volume=  1cm^{3} (1cm x 1cm x 1cm)

As cells increase in size, their surface area:volume ratios decrease rapidly; larger cells have a harder time moving molecules across the membrane, as there is less of a permeable surface for substances to diffuse across. In comparison to the other cell with a 6:1 ratio, this cell likely cannot obtain all the materials it requires.

Further Explanation:

Cells require all substances to cross the cell membrane. These are semi permeable -only allowing some molecules to pass cross the membrane or surface. Cell membranes contain lipids which form a barrier; polarity or arrangement can give these non-polar macromolecules hydrophilic and hydrophobic properties. Via diffusion, small water molecules can move across the phospholipid bilayer acts as a semi-permeable membrane into the extracellular fluid or the cytoplasm which are both hydrophilic and contain large concentrations of polar water molecules or other water-soluble compounds.

The hydrophilic heads of the bilayer are attracted to water while their water-repellent hydrophobic tails face towards each other- allowing molecules of water and water soluble molecules, to diffuse across the membrane along the concentration gradient. Thus in smaller cells, the rate of diffusion is higher as the surface area to volume ratio is higher; a substance can diffuse all the way to the center.

However as cells increase in size, their surface area:volume ratios decrease rapidly; larger cells have a harder time moving molecules across the membrane, as there is less of a permeable surface for substances to diffuse across. To combat this, eukaryotic cells have specialized mechanisms to transport molecules along with membrane-bound organelles like the endoplasmic reticulum that provide a higher surface area for absorption and enable more efficient transportation.

Learn more about membrane components at brainly.com/question/1971706

Learn more about plasma membrane transport at brainly.com/question/11410881

#LearnWithBrainly

3 0
3 years ago
What is the difference between a trade-off and an opportunity cost
Serga [27]

when we sacrifice one thing to obtain another, that's called a trade-off

Opportunity cost is an economic concept which used to discuss choice.


7 0
4 years ago
Read 2 more answers
How long ago was the Cambrian time in the geological time scale?
otez555 [7]

Answer:

About 540 to 490 million years ago

Explanation:

The Cambrian is the first and oldest division of the Paleozoic era on the geologic time scale. The other periods in the Paleozoic are the ordovician, silurian, devonian, carboniferous and permian. At the permian a mass extinction occured.

The cambrian is marked with the evolution of lot of life and it is typified by the presence and dominance of trilobites.

8 0
3 years ago
The part of the brainstem closest to the spinal cord is the _____; it is important for such functions as _____
Maksim231197 [3]

Answer:

1. Medulla

2. Heart rate and breathing

Explanation:

The brainstem is the part of the brain that was formed earlier in the history of the evolution of the brain, therefore, is present in the posterior region of the brain.  The brainstem is composed of three parts called the pons, the midbrain and the medulla.

The medulla is the portion which is connected to the spinal cord and thus the transfers the signals form the spinal cord to the brain structures.

The brainstem controls the main functions of the body like the breathing rate, the heart rate, consciousness, blood pressure and many involuntary functions.

Thus, Medulla and Heart rate and breathing are correct.

4 0
3 years ago
what is the relationship between the moose and wolf populations? Be sure to describe not only the population levels, but also th
ElenaW [278]
Well the relationship between them is predator and prey, the wolves being the predators and the moose’s being the prey. Predation can cause the preys population to decline, unless continued reproduction is occurring.
8 0
4 years ago
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