Plant And Animal Cell Quiz For Grade 7

Chlorophyll is a green pigment found in chloroplasts within plant cells. It absorbs light energy from the sun, which is essential for the process of photosynthesis. Photosynthesis converts light energy into chemical energy in the form of glucose, which plants use for growth and other functions.

Amoeba is a unicellular organism because it consists of only one cell. Unlike earthworms, snails, and elephants, which are multicellular organisms made up of many cells, amoeba is a single-celled organism that can perform all necessary functions of life within that one cell. Amoeba is a protist, a group of eukaryotic microorganisms, and it is known for its ability to change shape and move using pseudopods.

Structures in a cell are called organelles. Organelles are specialized structures within a cell that perform specific functions. They are like tiny organs within a cell, each with its own specific role. Examples of organelles include the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, and lysosomes. These organelles work together to carry out various cellular processes and maintain the overall functioning of the cell.

Robert Hooke is the correct answer because he was the first person to observe and describe cells in 1665. He used a microscope to examine thin slices of cork and noticed small compartments that he called "cells," because they reminded him of the small rooms monks lived in. Hooke's discovery of cells was a significant contribution to the field of biology and laid the foundation for the development of the cell theory.

All cells arise from pre-existing cells because of the principle of biogenesis, which states that living organisms can only arise from other living organisms. This principle was established through experiments conducted by Louis Pasteur in the 19th century, where he disproved the theory of spontaneous generation. Therefore, the correct answer is pre-existing cells.

The cell wall of a plant is composed of cellulose. Cellulose is a complex carbohydrate that provides structural support to the plant cell. It forms a rigid and strong framework around the cell membrane, allowing the plant to maintain its shape and withstand mechanical stress. Cellulose is made up of long chains of glucose molecules that are interconnected, forming a mesh-like structure. This composition of cellulose gives the plant cell wall its strength and durability.

Molecules are referred to as the electrically neutral group of two or more atoms held together by chemical bonds. In a molecule, the atoms share electrons to form stable bonds, resulting in a neutral overall charge. This is in contrast to ions, which have a positive or negative charge due to the loss or gain of electrons. Atoms are individual particles, while cells are the basic structural and functional units of living organisms.

The cell wall is peculiar to plant cells because it provides rigidity and support to the cell, which is necessary for the upright growth of plants. It is composed of cellulose and other polysaccharides, and it surrounds the cell membrane. Unlike animal cells, plant cells have a cell wall in addition to a cell membrane. The cell wall also helps protect the cell from mechanical stress and provides a barrier against pathogens.

Somatic cells undergo mitosis, which is a type of cell division that results in two identical daughter cells. This process is essential for the growth, repair, and maintenance of the body. During mitosis, the genetic material is duplicated and evenly distributed to each daughter cell, ensuring that they have the same genetic information as the parent cell. This allows somatic cells to continually replace damaged or old cells, ensuring the proper functioning of tissues and organs. 

Mitochondria are regarded as the powerhouses of the cell because they are responsible for producing the majority of the cell's energy in the form of ATP through a process called cellular respiration. They have their own DNA and can self-replicate, which suggests that they were once independent organisms that formed a symbiotic relationship with eukaryotic cells. Mitochondria have a highly folded inner membrane that increases their surface area, allowing for more efficient ATP production.

Both mitochondria and chloroplasts have similarities to prokaryotic cells because they both have their own DNA and ribosomes, which are similar to those found in prokaryotic cells. Additionally, both organelles are believed to have originated from endosymbiotic events where prokaryotic cells were engulfed by a eukaryotic cell and formed a symbiotic relationship. This is supported by the fact that mitochondria and chloroplasts have their own membranes and can replicate independently of the cell they reside in.

Cellulose is the correct answer because it is the main component of the cell wall, which is the outermost covering of a plant cell. Cellulose provides structural support and rigidity to the cell, helping to maintain its shape and protect it from external factors. Lignin is also present in the cell wall but is not the main component. Cytoplasm is the jelly-like substance inside the cell, not the outer covering. None of the above is incorrect because cellulose is indeed the correct answer.

The correct answer is Cytoplasm. The cytoplasm refers to all the contents of a cell that are enclosed by the plasma membrane, excluding the nucleus. It includes various organelles, such as mitochondria and ribosomes, as well as a gel-like substance called the cytosol. The cytoplasm plays a crucial role in supporting cellular processes and providing a medium for biochemical reactions to occur.

Protoplasm is the correct answer because it refers to the living portion of the cell. It includes the cytoplasm and the nucleus, which are responsible for carrying out the cell's functions and containing its genetic material. The term "cytoplasm" alone does not encompass the entire living portion of the cell, as it does not include the nucleus. "Cyst" is not related to the living portion of the cell, and the "nucleus" is only a part of the living portion, not the entire thing.

Each chromosome contains one DNA molecule.