Cellular Respiration, Excretion And Growth - SS1 Biology Past Questions and Answers - page 2
Explain the process of cellular respiration and its significance in maintaining cellular energy balance.
Cellular respiration is the metabolic process by which cells convert glucose and oxygen into carbon dioxide, water, and ATP (adenosine triphosphate). It consists of three main stages: glycolysis, the Krebs cycle (also known as the citric acid cycle), and oxidative phosphorylation (which includes the electron transport chain). Glycolysis occurs in the cytoplasm and breaks down glucose into pyruvate, producing a small amount of ATP. The pyruvate then enters the mitochondria, where the Krebs cycle takes place, generating more ATP and electron carriers (NADH and FADH2). These electron carriers donate electrons to the electron transport chain, located in the inner mitochondrial membrane. The electron transport chain generates a large amount of ATP through oxidative phosphorylation. Overall, cellular respiration provides cells with the necessary energy (in the form of ATP) to carry out various cellular processes.
Discuss the significance of cellular excretion in maintaining cellular homeostasis.
Cellular excretion refers to the removal of waste materials and metabolic byproducts from cells. This process is essential for maintaining cellular homeostasis by preventing the accumulation of toxic substances and maintaining optimal internal conditions. Cellular excretion involves various mechanisms such as diffusion, active transport, and exocytosis, which allow cells to eliminate waste products such as carbon dioxide, ammonia, urea, and excess salts. These processes ensure the proper functioning and survival of cells by preventing the build-up of harmful substances and maintaining a favorable cellular environment.
1. What is the difference between mitosis and meiosis?
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MITOSIS |
MEIOSIS |
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The purpose of mitosis is growth, tissue repair, and asexual reproduction. It produces identical cells |
The purpose of meiosis is the production of gametes (sperm and egg cells) for sexual reproduction. It creates genetically diverse cells |
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There is only one division, resulting in two daughter cells |
There are two divisions, resulting in four daughter cells |
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The chromosome number in daughter cells is the same as the parent cell (diploid) |
The chromosome number in daughter cells is reduced by half compared to the parent cell (haploid) |
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Genetic variation is minimal as the daughter cells are genetically identical to the parent cell |
Genetic variation is significant due to processes like crossing over, where genetic material is exchanged between chromosomes |
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Mitosis occurs in most cells of the body for growth and repair |
Meiosis occurs only in specialized cells called germ cells, which produce gametes |
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Daughter cells are genetically identical to each other and the parent cell |
Daughter cells are genetically different from each other and the parent cell |
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The resulting cells are diploid (two sets of chromosomes) |
The resulting cells are haploid (one set of chromosomes) |
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Mitosis can be involved in asexual reproduction, where offspring are genetically identical to the parent |
Meiosis is involved in sexual reproduction, where offspring inherit traits from both parents |