Grade 8 Science:Chapter 4 Quiz Cells

Explanation
This is an example of living things responding to changes in their environment. The plant is able to sense the presence of moist soil and grow its roots in that direction in order to obtain water and nutrients. This response to the environmental stimulus is a characteristic of living organisms, as they have the ability to detect and react to changes in their surroundings.

Explanation
The statement "The cells have a life span" is not an example of cell theory because cell theory does not address the lifespan of cells. Cell theory focuses on the idea that all living things are composed of cells, the cell is the basic unit of life, and all cells come from pre-existing cells. The lifespan of cells is a separate concept that is not directly related to the principles of cell theory.

Explanation
The maximum magnification of the microscope used in the science lab is 400X. This means that the microscope can enlarge an object up to 400 times its actual size. This level of magnification is commonly used in scientific research and allows for detailed observation of microscopic organisms and structures.

Explanation
When magnifying an object, the field of view decreases in size. This is because when we magnify an object, we are essentially zooming in on a smaller portion of the object, which results in a narrower field of view. As we increase the magnification, the area that we can see becomes smaller and more focused, leading to a decrease in the overall size of the field of view.

Explanation
The correct answer is "Cell wall, chloroplasts, cytoplasm, vacuole." The cell wall is a rigid structure found only in plant cells that provides support and protection. Chloroplasts are organelles responsible for photosynthesis, which is a process unique to plant cells. Cytoplasm is a jelly-like substance that fills the cell and is found in all types of cells, including plant cells. Vacuoles are large membrane-bound sacs that store water, nutrients, and waste materials, and they are more prominent in plant cells compared to animal cells. The other options include flagella and cilia, which are structures involved in cell movement, but they are not specific to plant cells.

Explanation
The cytoplasm is not an example of an organelle. Organelles are specialized structures within a cell that perform specific functions. The nucleus, chromosome, and vacuole are all examples of organelles. The nucleus contains the cell's genetic material, chromosomes are structures within the nucleus that carry genes, and vacuoles are membrane-bound organelles involved in storage and waste disposal. On the other hand, the cytoplasm is the gel-like substance that fills the cell and surrounds the organelles. While it plays a crucial role in supporting the organelles, it is not considered an organelle itself.

Explanation
Cilia are small hair-like structures found in the lungs of humans that help to remove dust particles and other foreign substances. These tiny projections beat in coordinated motions, creating a sweeping motion that moves mucus and trapped particles out of the respiratory system. This action helps to keep the lungs clean and prevents harmful substances from entering deeper into the respiratory tract.

Explanation
All of the listed organelles (mitochondria, lysosome, cell membrane, and flagella) are found in plant cells. This means that there is no organelle that is not found in a plant cell.

Explanation
Mitochondria can only be seen using an electron microscope because they are very small and have a complex internal structure. Electron microscopes use a beam of electrons to create an image, which has a higher resolution than light microscopes. This allows for the visualization of smaller structures like mitochondria. Vacuoles, chromosomes, and chloroplasts can be seen using both light and electron microscopes, as they are larger and more easily observable.

Explanation
Today's electron microscopes can magnify an object up to 2,000,000X.