Biology Lab Midterm Exam Study Guide

Explanation
The correct answer is TEM (Transmission Electron Microscope). In a TEM, the electron beam is passed through the sample, which allows for the formation of a 2D image. TEMs are used to study the internal structure of materials at a very high resolution, making them particularly useful in the field of nanotechnology and materials science.

Explanation
The DFV (Diameter Field of View) of a 10x lens can be calculated by multiplying the DFV of the 4x lens by the magnification factor. Since the magnification factor from 4x to 10x is 2.5 (10/4), the DFV of the 10x lens would be 4 mm multiplied by 2.5, which equals 10 mm. Therefore, the given answer of 1.6 mm is incorrect.

Explanation
The use of the condenser is to concentrate and direct the light through the specimen. The condenser is an important component in a microscope that helps to focus and control the amount of light that passes through the specimen. By concentrating the light, the condenser improves the resolution and clarity of the image. It also helps to evenly distribute the light, ensuring that the entire specimen is illuminated. This allows for better visualization and examination of the specimen under the microscope.

Explanation
Plasmodesmata are small channels that connect plant cells, allowing for the exchange of various molecules and substances between adjacent cells. These channels play a crucial role in cell-to-cell communication, nutrient transport, and overall coordination within the plant. Therefore, the given statement is true as it accurately describes the function of plasmodesmata in connecting plant cells.

Explanation
The correct answer is Cell wall. The cell wall is a rigid layer that surrounds the cell membrane in plant cells and provides structural support and protection. It helps maintain the shape of the cell and prevents it from bursting under pressure. The cell wall is absent in animal cells, which is why it is not found in cell number 1.

Explanation
The given statement is false because methylene blue is not used to stain the cytoplasm and nucleus of plant cells. Methylene blue is commonly used as a stain for animal cells, but not specifically for plant cells. Plant cells are typically stained using other dyes such as iodine or safranin. Therefore, the correct answer is false.

Explanation
The given answer, A+B, suggests that lipids have both stored energy and structural purposes. Lipids are known for their role in storing energy in the body, as they provide a concentrated form of energy that can be utilized when needed. Additionally, lipids also play a structural role in the form of the plasma membrane, which is composed of phospholipids. This answer implies that lipids serve multiple functions, including energy storage and structural support.

Explanation
The statement in the question is false. The cell membrane is actually made up of a phospholipid bilayer, consisting of two layers of phospholipids. Each phospholipid molecule has a hydrophilic (water-loving) head made of a phosphate group and a hydrophobic (water-fearing) tail made of two fatty acid chains. The glucose head mentioned in the question is not a component of the cell membrane structure.

Explanation
The statement is true because lemon has a higher concentration of vitamin C compared to orange and grapefruit.

Explanation
The variables that affect the function of an enzyme are its concentration, substrate concentration, and pH. Enzyme concentration refers to the amount of enzyme present in a reaction, which can directly influence the rate of the reaction. Substrate concentration refers to the amount of substrate available for the enzyme to bind to and convert into a product. The concentration of the substrate can affect the rate of the reaction, as a higher concentration can lead to more collisions between the enzyme and substrate. pH refers to the acidity or alkalinity of the environment in which the enzyme is working. Changes in pH can alter the shape and activity of the enzyme, affecting its function.

Explanation
Temperature is a measure of the average kinetic energy of molecules in a substance. The higher the temperature, the faster the molecules are moving. This movement is due to the kinetic energy they possess. Therefore, temperature can be considered as a measure of the speed at which molecules are moving.