Biology - Cells – Cell Practice Questions 2023.

Biology - Cells – Cell Practice Questions 2023.All living organisms are made up of what? - ANSWER One or more cells. Where do cells come from? - ANSWER The division of pre-existing cells. Describe the nucleus and its functions. - ANSWER A large organelle surrounded by a double layer membrane with pores for the selective intake and release of molecules (nuclear envelop). It does transcription and replication of genetic code. What does the nucleus contain? - ANSWER The nuclear envelop, nucleoplasm, chromatins, nucleolus. What is the function of nucleolus? - ANSWER Contain genetic material for the formation of ribosomal RNA (rRNA). Describe a ribosome. - ANSWER Small, dense-staining granules. It is composed of rRNA and some proteins joined together prior to the migration to the ER. Where are ribosomes found? - ANSWER On the surface of ER and free-floating in the cytoplasm in small groups called polyribosomes. What are the functions of ribosomes? - ANSWER Protein synthesis. What is a chromatin? - ANSWER A substance within chromosomes that contains DNA and histones densely coiled together. Only visible when condensed together for transport. Describe the Rough ER and its functions. - ANSWER A series of tubular canals connected in places with the nuclear membrane, covered in ribosomes. The ribosomes produce proteins, which move inside to the lumen of the ER, then onto the Golgi apparatus. Its function is to produce/modify proteins to be exported by the cell. Describe the Smooth ER and its functions. - ANSWER Similar to the Rough ER except with no ribosomes on its surface. It produces lipids and steroids. Abundant in steroid hormone-producing organs. Describe vacuoles and what their functions are. - ANSWER Non-living membrane-covered sacks usually filled with water and waste chemicals. Much larger in plants. Small vacuoles are vesicles. In plant cells, one vacuole may occupy 90% of the cell volume, giving rigidity to the cell (pressurized), stores waste products of metabolism, and makes the cytoplasm into a thin layer against the cell membrane to allow for better