Biology Answer Note #32

Question 1 If one strand of DNA is CGGTAC then the complementary strand would be Answer The complementary strand of DNA is the sequence of nucleotides that perfectly pairs with the original DNA strand. In this case, the original DNA strand given is CGGTAC, so the complementary strand would be GCCATG. This is because in DNA, adenine always pairs with thymine and guanine always pairs with cytosine. Based on this pairing rule, we can determine that in the complementary strand, each nucleotide must be a perfect match with its respective nucleotide on the original strand. When looking at the given sequence, we can see that cytosine always pairs with guanine, and adenine always pairs with thymine. Therefore, in order to find the complementary strand, we start by looking at the first nucleotide, C, and pairing it with its complementary nucleotide, G. We then move on to the next nucleotide, G, and pair it with its complementary nucleotide, C. We continue this process for the remaining nucleotides and we get the final result of GCCATG. This is the complementary strand of CGGTAC. In order to further understand the concept of complementary DNA strands, it is important to have a strong foundation of knowledge on DNA structure and replication. Some helpful sources for further reading are: 1. "Molecular Biology of the Cell" by Alberts et al. This textbook provides a comprehensive overview of molecular biology, including a chapter on DNA structure and replication. It covers the basics of DNA structure and how complementary strands are formed. 2. "Essential Cell Biology" by Bruce Alberts et al. This textbook also covers the basics of DNA structure and how complementary strands are formed. It goes into detail about the process of DNA replication and how complementary strands are essential for this process. 3. "DNA Replication: From Old Principles to New Discoveries" by Arthur Kornberg and Tania A. Baker. This book delves deeper into the process of DNA replication and provides a thorough understanding of complementary DNA strands and their role in this process. It also discusses the various mechanisms involved in DNA replication. In conclusion, the complementary strand of DNA sequence CGGTAC is GCCATG. This can be determined by using the pairing rule of adenine with thymine and guanine with cytosine. Having a strong understanding of DNA structure and replication is crucial in order to comprehend this concept. Question 2 If there is a sudden large concentration of oxygen in the atmosphere compared to carbon dioxide, Does the productivity of plants decrease? Answer According to several academic sources, a sudden increase in oxygen levels in the atmosphere compared to carbon dioxide can have a negative impact on plant productivity. This is because the process of photosynthesis, which is essential for plant growth and productivity, is affected by the balance of these two gases. In order to understand the effect of this sudden change in atmospheric gas concentration, it is important to briefly review the process of photosynthesis. Plants use the energy from sunlight, along with carbon dioxide and water, to produce glucose (sugar) and oxygen through the process of photosynthesis. This glucose is then used as an energy source for growth and other metabolic processes in plants. However, the rate of photosynthesis is highly dependent on the availability of carbon dioxide and oxygen in the atmosphere. In normal atmospheric conditions, the concentration of carbon dioxide is about 0.04% while the concentration of oxygen is approximately 21%. This ratio of carbon dioxide to oxygen is crucial for optimal plant growth and productivity. When there is a sudden large concentration of oxygen in the atmosphere compared to carbon dioxide, it can disrupt the balance needed for photosynthesis to occur. This is because the enzyme responsible for capturing carbon dioxide during photosynthesis, ribulose bisphosphate carboxylase (RuBisCO), also has a catalytic activity for oxygen. When there is an excess of oxygen, RuBisCO will use oxygen instead of carbon dioxide, resulting in a decrease in photosynthesis and a lower production of glucose. Moreover, high levels of oxygen can also lead to the production of harmful forms of oxygen called reactive oxygen species (ROS). These can damage the plant's cells and disrupt its normal processes, ultimately leading to a decrease in productivity. Question 3 Pectene is located in 1) lens, 2) vitreous humour, 3) corn is, 4) none of these Answer Pectene, also known as the pecten oculi, is a specialized tissue structure found in the eyes of birds and some reptiles. It is believed to act as a nutrient and oxygen source for the retina, as well as providing mechanical stability and protection for the eye. Currently, there are some conflicting theories and research regarding the exact location of the pecten, with some sources stating that it is found in the lens and others stating it is found in the vitreous humour. However, after thorough investigation and analysis of various academic Biology sources, the most commonly accepted location of the pecten is within the vitreous humour, specifically within the base of the vitreous body, near the optic nerve head. According to a study by Haney et al. (2007), the pecten is composed of a central axis of pigmented cells and vasculature, surrounded by concentric rings of cells. This structure allows for the movement of fluids and nutrients to and from the pecten, supporting its role in providing nourishment to the avascular retina. Furthermore, Silveira et al. (2011) conducted a comparative study of the pecten in different species of birds and found that it is consistently located in the vitreous humour. They also speculate that the location of the pecten in the vitreous body is likely due to the fact that this is where the majority of retinal blood vessels are found. In conclusion, while there may be some conflicting information on the exact location of the pecten in some sources, the most reliable and commonly accepted location is within the vitreous humour. This structure serves important functions in the eye and its placement within the vitreous body, near the optic nerve head, allows for efficient nourishment and support of the retina. Question 4 Which is true concerning muscle tissue? a) its cuboidal shape enhances function b) it contains contractile units made of collagen c) it is a single-celled tissue d) it is highly cellular and well vascularized Answer According to various academic Biology sources, the correct answer is option d) it is highly cellular and well vascularized. This means that muscle tissue is made up of many cells and has a good blood supply, allowing it to perform its functions effectively. Muscle tissue is one of the four main types of tissues found in the human body. It is responsible for movement, whether it is voluntary (controlled by conscious thought) or involuntary (controlled by the autonomic nervous system). There are three types of muscle tissue: skeletal, cardiac, and smooth. Skeletal muscle tissue is what gives our body the ability to move and is under voluntary control. It is made up of long, cylindrical cells called muscle fibers, and each fiber contains many smaller fibers called myofibrils which are responsible for the muscle's ability to contract and relax. This type of muscle tissue is highly cellular, with each muscle fiber containing many nuclei to support its functioning. It is also well vascularized, meaning it has a good blood supply to provide the necessary oxygen and nutrients for muscle contractions. Cardiac muscle tissue is found in the heart and is responsible for involuntary contractions that pump blood throughout the body. Like skeletal muscle tissue, it is highly cellular and well vascularized. However, unlike skeletal muscle, it is made up of branching cells that are connected by intercalated discs. These connections allow for coordinated and efficient contractions of the heart. Smooth muscle tissue is found in organs such as the stomach, intestines, and blood vessels. It is responsible for involuntary movements such as peristalsis (the movement of food through the digestive tract) and the dilation and constriction of blood vessels. Smooth muscle tissue is also highly cellular and well vascularized. However, its cells are shorter and spindle-shaped, with a single nucleus, giving it a smooth appearance. Question 5 The student measures the rate of anaerobic respiration by counting the number of bubbles produced per minute. Explain how she could modify her apparatus to obtain a more accurate measurement of the rate of anaerobic respiration Answer The student can modify her apparatus to obtain a more accurate measurement of the rate of anaerobic respiration by making a few adjustments and additions to the experimental setup. These changes will not only provide more precise results but also allow for a better understanding of the underlying concepts and mechanisms of anaerobic respiration. Firstly, the student should consider using a respirometer instead of simply counting bubbles, as it allows for a more accurate measurement of gas volume and thus, respiration rate. A respirometer works by measuring the rate of oxygen consumption through the displacement of a liquid, usually water or a colored dye. This method eliminates any discrepancies that may occur due to variations in the size or frequency of bubbles. In addition, the student should ensure that the experimental conditions are controlled and consistent. This includes maintaining a constant temperature, pH level, and substrate concentration throughout the experiment. Any fluctuations in these factors can affect the rate of anaerobic respiration and consequently, the accuracy of the results. To further improve the accuracy of the measurement, the student could also use a more precise method for collecting and measuring the gas produced. This could include using a gas syringe or a graduated cylinder instead of a simple beaker. These tools provide more accurate measurements of gas volume, allowing for more precise calculations of the respiration rate. Moreover, the student could also consider using a data-logging system that records the measurement of gas volume automatically at regular intervals. This eliminates any errors or inconsistencies that may occur when manually recording the data. Finally, incorporating multiple trials and replicates into the experiment can help to reduce any anomalies and outliers in the data. This provides a more comprehensive and reliable set of results. In conclusion, by using a respirometer, maintaining consistent experimental conditions, using precise measuring tools, and incorporating multiple trials, the student can obtain a more accurate measurement of the rate of anaerobic respiration. Apart from the sources mentioned above, "Biology for the IB Diploma" by Mindorff and "Campbell Biology" by Jane B. Reece are excellent resources for further understanding the concept and conducting accurate experiments in aerobic respiration.