The nucleus found in the cell is similar to the brain of a person. Nucleus controls most of the cell’s growth and activity. It contains the genetic material of the cell, which is coded with the instructions needed for protein synthesis to produce chromosomes and other important molecules.

D. nucleus

The cell wall is only found in plant cells, whereas mitochondria and nucleus are only present in eukaryotic cells. Therefore, the correct answer is cell membrane. Cell membranes are found in all cells. It serves as the barrier that protects the cell from the external environment.

B. cell membrane

Eukaryotes such as plants and animals have DNA which is located inside the nucleus. On the other hand, prokaryotes lack a nucleus so their genetic material is found in the cytoplasm.

B. eukaryote

The distinct threadlike structures that contain the genetic material in the nucleus of a cell is called the chromosomes.

B. chromosomes

Mitochondria are the organelles that function as the powerhouse of the cell. They convert the chemical energy from the food into an energy in the form of ATP in which the cells can use in order to do its work.

C. mitochondrion

A cell membrane is composed of a lipid bilayer or two layers of lipids which contain proteins and carbohydrate chains.

A. lipid bilayers

Osmosis refers to the diffusion of water molecules across a selectively permeable membrane.

D. osmosis

When ions or molecules move from high to low concentration, it does not require energy. The movement of the molecules is away from the area that is more concentrated.

C. away from the area where it is more concentrated

The correct answer is D. The stomata, which is found in the leaves, is a pore that opens and closes to facilitate gas exchange in plants. Moreover, choice A shows a unicellular organism called Leptospira interrogans, choice B is a muscle cell, while choice C is a red blood cell.

D. stomata

The level of organization in a multicellular organism starts with the individual cells. In turn, when similar cells are grouped together, they make a tissue.

A. similar cells

Here is a sample table that summarizes the contributions of Hooke, Schleiden, Schwann, and Virchow in the cell theory:

Prokaryotic and eukaryotic cells are the same because they both have cell membranes, cytoplasm, and contain DNA. They are different because they’re DNA are found in different places of the cell. Prokaryotic cells store their DNA in the nucleus. Since eukaryotic cells have no nucleus, their DNA is stored in the cytoplasm.

The nucleus controls most of the cell’s growth and activities. It contains the genetic material of the cell, which is coded with the instructions needed for protein synthesis to produce chromosomes and other important molecules. Here are the parts of a nucleus:

a. Nuclear envelope: It is a double-membrane structure that serves as the outermost layer of the nucleus

b. Nucleoplasm: It is a fluid found inside the nucleus where the chromatin and nucleolus are found

c. Chromatin: It is the genetic material which consists of DNA and proteins. The threadlike chromatins condense to form chromosomes.

d. Nucleolus: It is the dark stained area in the nucleus which helps synthesize the ribosomes.

A ribosome, which is usually found in the cytoplasm, is mainly responsible for protein synthesis. It produces protein by following the coded instructions from the DNA.

The rough endoplasmic reticulum assembles and gives way to the chemical compounds such as lipid components of the cell membrane, proteins, and other materials that are exported from the cell.

The Golgi apparatus, which appears as a stack-like structure, is the organelle that prepares, modifies, and sorts proteins from the endoplasmic reticulum. Later on, these materials stored in this organelle are shipped to their next destination, which is outside the cell.

According to Lynn Margulis, the mitochondria and the chloroplasts were once free-living cells that attached themselves to the cells. These two organelles have similarities with a bacteria cell, which suggests that they were primitive bacteria cells since both of them have their DNA separated from the ones found in the nucleus. Their DNA produce proteins and enzymes that are needed for the function of these two organelles.

made from actin filament that forms a threadlike structure that forms an extensive network, producing a tough, flexible framework supporting the cell

made of tubulins. These hollow structures help maintain cell shape and plays a role in cell division, forming the mitotic spindle

please see explanation

Cell membrane is made from a phospholipid bilayer. It provides, protection and flexibility to the cell. It is semi-permeable, only allowing certain things to pass. It also has protein channels that allow certain molecules in/out. There are also carbohydrates embedded throughout the membrane acting as chemical identifications cards, permitting cells to identify each other

please see explanation

The term concentration is defined as the ratio of the amount of solute in relation to the solution. An example of concentration is the amount of salt in a saltwater solution. The concentration of a solution can be identified by determining the mass of a solute, which is in grams, that is dissolved in a given volume of solution. If 2 grams of salt was dissolved in 4 liters of water, the concentration of the solution is 0.5 g/L.

Formula:
Concentration = mass of the solute (g) / volume of the solution (L)
= 2 g / 4 L
= 0.5 g/L

The term concentration is defined as the ratio of the amount of solute in relation to the solution. An example of concentration is the amount of salt in a saltwater solution. The concentration of a solution can be identified by determining the mass of a solute, which is in grams, that is dissolved in a given volume of solution. If 2 grams of salt was dissolved in 4 liters of water, the concentration of the solution is 0.5 g/L.

In diffusion, the ions or molecules move from high to low concentration. This means that the movement of the molecules is away from the area that is more concentrated. This process does not require energy. The diffusion is considered complete when it is in the state of equal concentration or equilibrium. This indicates that there is an equal movement of molecules in both directions.

**Passive transport** is a type of cell transport that does not need the energy to move and carry substances across cell membranes.

Examples of passive transport are **diffusion and osmosis**.

**Diffusion** is where the substances move from a higher concentration area to a lower concentration in a given solution.

While **osmosis** is the travel of water through a selectively permeable membrane from more to a less concentrated area.
Hence, in osmosis, only water can move in the setup.

The term isotonic means that two concentrations have the same strength on both sides of the cell membrane. For an instance, if a plant cell is put in a sugar solution that is isotonic, the cell would not change in size. It will stay the same and the direction of water molecules coming in and out of the cell would be equal.

The cell wall, which is the tough layer that surrounds the cell membrane, is responsible for keeping and maintaining the shape of the plant cell. When the cell is full of water due to osmotic pressure, the cell wall becomes turgid as it restricts the expansion. This process allows the plant cell to protect itself against bursting out due to the pressure.

The level of organization in a multicellular organism starts with the individual cells. When cells that have similar functions are grouped together, they make a tissue, and tissues form an organ. A group of organs with a similar function is called an organ system.

Here are some examples:
a. muscle cells, muscle tissues, muscular system
b. nerve cells, nerve tissues, nervous system
c. bone cells, bone tissues, skeletal system

The level of organization in a multicellular organism starts with the individual cells. When cells that have similar functions are grouped together, they make a tissue, and tissues form an organ. A group of organs with a similar function is called an organ system, e.g. muscle cells, muscle tissues, muscular system.

Since Side A is hypertonic, the water molecules from Side B goes to Side A. Water molecules tend to move across the membrane to the left side, where the salt concentration is high, until the state of equilibrium is reached. Equilibrium happens once the concentration of the solute is the same in the system. As a result, the fluid level in Side A will be greater than the fluid level in Side B.

Salt solution A

Given:

Mass of solute = 18 grams of salt

Volume of solution = 6 liters of water.

Formula:

Concentration = mass of solute (g) / volume of solution (L)

Solve:

= 18 g / 6 L

= 3 g/L

To get the concentration, we have to divide the mass of the solute to the volume of the solution. Since solution A contains 18 grams of salt in 6 liters of water, the concentration is 3 g/L.

Salt solution B

Given:

Mass of solute = 24 grams of salt

Volume of solution = 12 liters of water.

Formula:

Concentration = mass of solute (g) / volume of solution (L)

Solve:

= 24 g / 12 L

= 2 g/L

To get the concentration, we have to divide the mass of the solute to the volume of the solution. Since solution B contains 24 grams of salt in 12 liters of water, the concentration is 2 g/L.

Salt solution A contains a concentration of 3 g/L, whereas salt solution B contains 2 g/L. Therefore, solution A is more concentrated than solution B.

The solution is considered as **hypotonic** is the solute concentration outside the cell is lower than inside the cell. Hence, there will be a net flow of water molecules into the cell, resulting in its volume gain.

If the blood cells were put in a hypotonic solution they would swell and burst since the concentration of solute is higher inside the cell, and the water outside the cell will tend to diffuse into the cell rendering a gain in its volume which can damage its lining and eventually caused its burst.

**Mitochondria** is also known as the “powerhouse of the cell”. It produces most of the chemical energy needed by the cell’s reaction and processes

Yes, there are reports that say that muscle cells contain more mitochondria compared to skin cells. This excess number of mitochondria is needed by the muscle cells in order to meet their energy requirements.

Below is a sample of a simple experiment about diffusion:

Since diffusion is caused by the movement of ions or molecules from an area of higher concentration to a lower concentration, adding heat to it can increase the motion of these molecules. As a result, the rate of diffusion happens faster if there is an increase in temperature.

Hypothesis: The presence of a high temperature will make the rate of diffusion faster.

In this experiment, we will determine the effect of a hot temperature on the rate of diffusion.

Materials needed:
a. 3 beakers
b. vegetable coloring in three different colors (blue, red, yellow)
c. 100 mL of hot water
d. 100 mL of cold water
e. 100 mL of room temperature water
f. dropper
g. timer

Steps:
1. Prepare the food coloring and the beakers. Label the beakers with A, B, and C. Beaker A will serve as the controlled group.
2. Beaker A must be poured with 100 mL of room temperature water.
3. Place one drop of the yellow color into beaker A.
4. Use the timer and see how much time it takes until the water gets a consistent yellow color. Record the time in seconds.
5. Pour the cold water in beaker B and place one drop of blue color in it. Record the time until the water gets a consistent blue color.
6. Pour the hot water in beaker C and place one drop of red color in it. Record the time until the water gets a consistent red color.
7. Compare the results and determine which beaker has the lowest time.

The organelles responsible for producing enzymes in the pancreas are the rough endoplasmic reticulum and Golgi apparatus. Pancreas have an increased number of these organelles, compared than other cells. The reason why they have more rough ER and Golgi apparatus is because these organelles are making, sorting and packaging large amounts of enzymes in the form of proteins. These enzymes are secreted by the pancreas to aid in the digestion.

Here is a sample analogy to describe the functions of the different parts of a cell :

A cell is compared to a restaurant.

1. The cell membrane is like the restaurant doors. It controls what gets in and gets out of the cell, which is just like how the restaurant doors control who goes in and goes out of the restaurant.
2. The cytoplasm is compared to the restaurant floor. It holds the organelles together in place, which is just like the restaurant floor that holds all the tables, chairs and other equipment.
3. The nucleus controls the cell’s activities, just like a restaurant manager who oversees what happens inside the restaurant.
4. Ribosomes produce the proteins, which is similar to the work of the chef who cooks the food.
5. Mitochondria serve as the powerhouse of the cell. It stores energy obtained from the food which is going to be used by the other organelles. It is similar to the function of the refrigerator which stores the food until it is needed to be cooked.
6. The endoplasmic reticulum is the place where proteins and other compounds are produced. This is similar to the function of the kitchen wherein all the foods are prepared and cooked.
7. The Golgi apparatus prepares, modifies, and sorts proteins from the endoplasmic reticulum, which is similar to a waiter. The waiter ensures that all orders are sorted and served to the hungry customers.

A cell is compared to a restaurant.

In general, cells maintain homeostasis by regulating its water flow and controlling the movement of substances through the cell membrane. If a cell contains a build up of waste chemicals, they use diffusion and osmosis to get rid of these wastes. Cells convert the waste product into a molecule which can be diffused easily by the body. Since most chemicals can be dissolved in water, the diffusion happens through sweating. Our bodies use water, which is in the form of sweat, to flush away the toxins and chemical wastes in our body.

Passive Transport, also known as diffusion, refers to the movement of ions and molecules from high concentration to low concentration, without using metabolic energy. An example of passive transport is the exchange of oxygen and carbon dioxide inside the alveoli in our lungs. Because of passive transport, oxygen and other nutrients are diffused into our cells. On the contrary, active transport moves ions and molecules from low concentration to high concentration using a metabolic energy in the form of ATP. Phagocytosis and pinocytosis are examples of active transport. Phagocytosis is the cell’s way of engulfing or eating a particle. An example of this is the white blood cell’s way of ingesting a bacteria. On the other hand, pinocytosis is the cell’s process of taking up liquid from its surrounding environment. An example of this is the way our body cells absorb enzyme and hormones. Without these processes, our bodies would have a difficult time maintaining homeostasis and adapting to the outside conditions.