Biology Answer Note #12

Question 1 Q1.1 (a) How does the structure of cell membranes influence the selective permeability and movement of substances across them? b) Explain how organelles in eukaryotic cells work together to produce, process, transport, and release proteins. Answer The cell membrane is a crucial component of the cell, as it acts as a barrier and controls the movement of substances in and out of the cell. The structure of the cell membrane plays a critical role in its function of selective permeability. The cell membrane is made up of a lipid bilayer, which is primarily composed of phospholipids with hydrophilic heads and hydrophobic tails. This arrangement allows the cell membrane to be selectively permeable, as it only allows certain substances to pass through while preventing others from entering or leaving. Additionally, the cell membrane also contains integral and peripheral proteins, which are responsible for facilitating the transport of molecules across the membrane. Integral proteins act as channels or carriers, allowing specific molecules to pass through the membrane via facilitated diffusion or active transport. Peripheral proteins, on the other hand, act as enzymes or signaling molecules, contributing to the selective permeability of the cell membrane. Furthermore, the fluidity of the cell membrane also plays a crucial role in its selective permeability. As the cell membrane is composed of a lipid bilayer, it has a fluid-like nature, allowing for the easy movement of molecules within the membrane. This fluidity is regulated by the presence of cholesterol, which maintains the proper spacing between the phospholipids. This regulated fluidity is essential for signal transduction and maintaining the integrity of the cell membrane. In summary, the structure of the cell membrane, with its lipid bilayer, integral and peripheral proteins, and regulated fluidity, allows for selective permeability, where only certain molecules can pass through. This selective permeability is crucial for maintaining the cell's internal environment and enabling proper physiological functions. (b) Explain how organelles in eukaryotic cells work together to produce, process, transport, and release proteins. Eukaryotic cells contain various organelles that are specialized in performing specific functions. In the production, processing, transport, and release of proteins, several organelles work together in a coordinated manner. Firstly, the nucleus of the cell contains the genetic material, DNA, which carries the instructions for protein synthesis. The DNA is transcribed into mRNA, which then leaves the nucleus through nuclear pores and enters the cytoplasm. In the cytoplasm, the mRNA attaches to ribosomes, which are either free in the cytoplasm or attached to the rough endoplasmic reticulum (ER). The ribosomes read the mRNA sequence and synthesize the protein accordingly. The rough ER plays a vital role in the processing of proteins as it contains ribosomes attached to its outer surface. This allows for the synthesis and processing of proteins simultaneously. The proteins are then transported through the ER, where they undergo further modifications, such as folding and adding of carbohydrates. Once processed, the proteins are transported to the Golgi apparatus, the organelle responsible for sorting, modifying, and packaging proteins. Here, the proteins undergo further modifications, such as the addition of specific molecules, before being packaged into vesicles for transport. The vesicles containing the processed proteins fuse with the cell membrane and release the proteins to the extracellular space through exocytosis. Alternatively, the proteins can also be targeted to specific organelles within the cell, such as mitochondria or lysosomes, for further processing. In summary, the coordinated efforts of the nucleus, ribosomes, ER, Golgi apparatus, and cell membrane work together to produce, process, transport, and release proteins. Each organelle contributes to specific functions, ensuring the proper production and release of functional proteins. Question 2 Which tRNA anticodon is complementary to the UGC triplet? Select one answer: a. UGC b. UAC c. CSU d. ACG Clear my selection Question 11 No answer yet Score: 1 Not markedFlag question Question text An individual with the AABB genotype Select one answer: a. forms two types of gametes b. forms one type of gametes c. heterozygous d. homozygous for a recessive trait Clear my selection Question 12 No answer yet Score: 1 Not markedFlag question Question text From a marriage between a man with II and a woman with I blood groups, the children may have the following genotype(s) Select one answer: a. IАIВ b. I0I0 c. IВI0 d. IАIА Answer The tRNA anticodon that is complementary to the UGC triplet is answer a. UGC. Explanation: tRNA (transfer RNA) plays an important role in protein synthesis by carrying specific amino acids to the ribosome. The sequence of three nitrogenous bases on tRNA, known as the anticodon, is complementary to the codon sequence on mRNA. This ensures the correct amino acid is brought to the ribosome during translation. In this case, UGC is the codon on mRNA that codes for the amino acid cysteine, therefore the complementary anticodon on tRNA is UGC. This specific pairing is essential for accurate protein synthesis. Question 3 1. The net effect of photosynthesis, chemically, is reduction, leading to the formation of which products? a. Carbon dioxide and carbohydrates b. Carbon dioxide and protein c. Oxygen and carbohydrates d. Oxygen and ATP Answer 1. The net effect of photosynthesis, chemically, is reduction, leading to the formation of which products? The correct answer is c. Oxygen and carbohydrates. Photosynthesis is a biochemical process that occurs in plant cells, specifically in the chloroplasts, where light energy is converted into chemical energy in the form of adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide phosphate (NADPH). This enables the synthesis of organic compounds, such as carbohydrates, from carbon dioxide and water. In photosynthesis, the energy from sunlight is used to drive the reduction of carbon dioxide, resulting in the production of oxygen and carbohydrates. To better understand the process, let's break it down step by step: Step 1: Absorption of Light Photosynthesis begins with the absorption of light by chlorophyll pigments located in the thylakoid membranes of the chloroplasts. The absorbed light energy is used to split water molecules into hydrogen ions (H+), electrons (e^-), and oxygen gas (O2). This process is known as photolysis. Step 2: Light-Dependent Reactions In the light-dependent reactions of photosynthesis, the energized electrons and hydrogen ions are used to generate ATP and NADPH. The electron transport chain located in the thylakoid membranes is responsible for this production. Step 3: Light-Independent Reactions The ATP and NADPH produced in the light-dependent reactions are then used to drive the light-independent reactions, also known as the Calvin cycle. In this stage, carbon dioxide is reduced and converted into carbohydrates, such as glucose. So, the net effect of photosynthesis is the reduction of carbon dioxide into organic compounds (carbohydrates) and the production of oxygen gas as a byproduct. Question 4 Skip to main content https://unilag.edu.ng communicationsunit@unilag.edu.ng logo Toggle messages menu Toggle notifications menu Oluwafisayomi Opeyemi Omolayo Picture of Oluwafisayomi Opeyemi Omolayo Testonline Search courses Submit Page path Home My courses BTN_2023/2024 General CLICK HERE TO START BTN121 TEST - GROUP A (BIOCHEMISTRY, BOTANY, CELL BIOLOGY, DENTISTRY) Question 1Not yet answeredMarked out of 1Not flaggedFlag question Question text Which of the following is true regarding seed development in angiosperms? Select one: a. Seeds are enclosed within the ovary b. Seeds are "naked" and not enclosed in an ovary c. Seeds develop on leaves or scales d. They often exist in cone form Question 2Not yet answeredMarked out of 1Not flaggedFlag question Question text One of these is NOT a Pteropsida: Select one: a. Azolla b. Nephrolepis, c. Selaginella, d. Pteris, Question 3Not yet answeredMarked out of 1Not flaggedFlag question Question text The cell wall of fungus is surrounded by distinct cell wall which compose of Select one: a. Glycogen b. Glucan c. Chitin d. Cellulose Question 4Not yet answeredMarked out of 1Not flaggedFlag question Question text What constitute the Viral genome? Select one: a. Both DNA and RNA b. RNA or DNA c. DNA d. RNA Question 5Not yet answeredMarked out of 1Not flaggedFlag question Question text The main plant body of angiosperm is Select one: a. Haploid and sporophytic b. Haploid and gametophytic c. Diploid and gametophytic d. Diploid and sporophytic Question 6Not yet answeredMarked out of 1Not flaggedFlag question Question text What does it mean for a fungi to be ubiquitous? Select one: a. When it is restricted to a certain area b. When it is taken as food c. When it is found everywhere d. When it exist in the soil Question 7Not yet answeredMarked out of 1Not flaggedFlag question Question text Artificial propagation in angiosperm can be by Select one: a. Stem cutting b. Tissue culture c. Grafting d. All of the above Question 8Not yet answeredMarked out of 1Not flaggedFlag question Question text What helps in cell motility in bacteria? Select one: a. cell shapes b. organelles c. cytosol d. flagella Question 9Not yet answeredMarked out of 1Not flaggedFlag question Question text Staphylococci refers to what shaped of bacteria? Select one: a. cells in clusters b. pairs of cocci c. cells in chains d. none of the above Question 10Not yet answeredMarked out of 1Not flaggedFlag question Question text Which of these ia also known as amphibious plants Select one: a. Mesophytes b. Halophytes c. Xerophytes d. Hydrophytes Question 11Not yet answeredMarked out of 1Not flaggedFlag question Question text Which is a characteristic of the dicotyledoneae Select one: a. One cotyledon b. Presence of fibrous root system c. Presence of secondary growth d. Flowers are trimerous Question 12Not yet answeredMarked out of 1Not flaggedFlag question Question text Tinsel flagella is also known as Select one: a. None of the above b. Pantonematic c. Acronematic d. Whiplash Question 13Not yet answeredMarked out of 1Not flaggedFlag question Question text What is the family of the Lassa fever virus Select one: a. Arenaviridae b. Calciviridae c. Cucumoviridae d. Bromoviridae Question 14Not yet answeredMarked out of 1Not flaggedFlag question Question text In ferns, the sporophytic generation is Select one: a. diploid, b. triploid, c. monoploid, d. minute Question 15Not yet answeredMarked out of 1Not flaggedFlag question Question text The water around the marshy environment is Select one: a. Neutral or alkaline b. Salty c. Basic d. Acidic Question 16Not yet answeredMarked out of 1Not flaggedFlag question Question text The smallest angiosperm is about: Select one: a. 30m in diameter b. 0.5cm in diameter c. 0.1cm in diameter d. 5m in diameter Question 17Not yet answeredMarked out of 1Not flaggedFlag question Question text A single flagellum on one side of the bacterial cell is refer to as Select one: a. amphitrichous b. monotrichous c. peritrichous d. lophotrichous Question 18Not yet answeredMarked out of 1Not flaggedFlag question Question text In Dryopteris, sori are located Select one: a. terminally b. abaxially, c. adaxially, d. marginally, Question 19Not yet answeredMarked out of 1Not flaggedFlag question Question text Branching in Lycopodium is Select one: a. heterochotomous b. monopodial c. monopodial and dichotomous d. dichotomous Question 20Not yet answeredMarked out of 1Not flaggedFlag question Question text The symmetry of the Coronavirus is Select one: a. Isometric b. Helical c. Bilateral d. Icosahedron Question 21Not yet answeredMarked out of 1Not flaggedFlag question Question text Why are the groups of plants in 20 above called amphibious? Select one: a. Because they can grow in both arid and semi-arid environments b. Because they grow in water or very wet places. c. Because they float on the surface of water alone d. Because they can grow in saline environments and lagoon water Question 22Not yet answeredMarked out of 1Not flaggedFlag question Question text Artificial propagation in angiosperm can be by the following except Select one: a. Layering b. Stem cutting c. Budding d. Grafting Question 23Not yet answeredMarked out of 1Not flaggedFlag question Question text The COVID-19 virus is in the family— Select one: a. Sarividae b. Rhabdoviridae c. Calciviridae d. Coronaviridae Question 24Not yet answeredMarked out of 1Not flaggedFlag question Question text What are mesophytes? Select one: a. Plants that grow under average conditions of temperature and moisture b. Plants that grow on another plant c. Plants that grow in marshy environments throughout the periods of the year d. Drought-tolerant plants Question 25Not yet answeredMarked out of 1Not flaggedFlag question Question text Cryptogams are all except one: Select one: a. primitive b. higher plants c. flowerless d. seedless Question 26Not yet answeredMarked out of 1Not flaggedFlag question Question text Which of the following is an example of phytoplankton? Select one: a. Chara b. Chlorella c. Porphyra d. Laminaria Question 27Not yet answeredMarked out of 1Not flaggedFlag question Question text Plants that grow constantly in moist shady environments are called? Select one: a. Halophytes b. Hygrophytes c. Mesophytes d. Xerophytes Question 28Not yet answeredMarked out of 1Not flaggedFlag question Question text The highly resistant resting stage in bacteria is called Select one: a. spore b. all of the above c. granule d. log phase Question 29Not yet answeredMarked out of 1Not flaggedFlag question Question text What is the Size of a Virus? Select one: a. 2nm-18nm b. 75 nm c. 20nm-300nm d. 700nm Question 30Not yet answeredMarked out of 1Not flaggedFlag question Question text Diatom cell wall is made up of Select one: a. Silica b. Cellulose c. Alginic acid d. Mucopeptide Question 31Not yet answeredMarked out of 1Not flaggedFlag question Question text Plants that grow in the desert or driest environment are called Select one: a. Xerophytes b. Hygrophytes c. Mesophytes d. Halophytes Question 32Not yet answeredMarked out of 1Not flaggedFlag question Question text The perfect state spore in sub-division Mastigomycotina is Select one: a. Basidiospore b. Zoospores c. Teliospores d. Oospore Question 33Not yet answeredMarked out of 1Not flaggedFlag question Question text Which of these is a not a primitive character in Psilotum? Select one: a. Presence of cambium and secondary growth, b. Homomorphic type of alternation of generation c. Protostelic condition of the rhizome, d. Xylem made of annular and spiral tracheids, Question 34Not yet answeredMarked out of 1Not flaggedFlag question Question text The red algae belong to the Division Select one: a. Pyrrophyta b. Rhodophyta c. Chlorophyta d. Bacillariophyta Question 35Not yet answeredMarked out of 1Not flaggedFlag question Question text Bacterial spores consist of how many layers? Select one: a. 5 b. 2 c. 4 d. 3 Question 36Not yet answeredMarked out of 1Not flaggedFlag question Question text Prions are Select one: a. Eukaryotes b. Infectious proteins c. Eucaryotes d. Parasites Question 37Not yet answeredMarked out of 1Not flaggedFlag question Question text A group of bacteria with cell wall deficient thereby lack stable morphology Select one: a. actinomycetes b. blue-green c. mycoplasmas d. spirochetes Question 38Not yet answeredMarked out of 1Not flaggedFlag question Question text Which of these determines bacteria cell shape? Select one: a. flagellum b. cell wall c. protoplasm d. capsule Question 39Not yet answeredMarked out of 1Not flaggedFlag question Question text Example of the Virus shape which is Flexuous phage is Select one: a. Lettuce virus b. Potato virus X c. Tobacco Mosaic Virus d. Alfalfa Mosaic Virus Question 40Not yet answeredMarked out of 1Not flaggedFlag question Question text Bacteria with thin wall layer and outer membrane stain red are referred to as Select one: a. gram negative b. gram positive c. protoplast d. spheroplasts Answer The development of seeds is a crucial stage in the life cycle of angiosperms, also known as flowering plants. Through the process of reproduction, angiosperms produce seeds which eventually develop into new plants. There are various distinguishing features that characterize the development of seeds in angiosperms, and one of them is the location of the seeds. According to the research article from the National Center for Biotechnology Information, angiosperms have enclosed seeds that are protected within the ovary, a structure found in the female part of the flower. The ovary serves as a protective layer for the developing seed, shielding it from external harm and providing essential nutrients for its growth. This unique characteristic of angiosperms is one of the main reasons for their evolutionary success, allowing them to reproduce and spread to different environments. In contrast, gymnosperms, another type of seed-producing plant, have "naked" seeds, meaning they are not enclosed in an ovary but rather exposed for protection. This is a significant difference between angiosperms and gymnosperms, and one that highlights the advanced level of development in angiosperms. In conclusion, it is evident that seeds in angiosperms are enclosed within the ovary, which serves as a protective and nourishing structure for the developing seeds. This is a unique and crucial characteristic in the success of angiosperms as a dominant plant group in the world. Question 5 What feature is FALSE regarding red blood cells: Question 4 options: they have hemoglobin in order to remain flexible through capillaries they are biconcave to increase surface area they have no nucleus to make room for carrying more oxygen they have no mitochondria, as to limit oxygen consumption Answer The feature that is FALSE regarding red blood cells is that they have no mitochondria, as to limit oxygen consumption. This statement is incorrect because red blood cells do contain a small amount of mitochondria, although it is not enough for energy production. According to the medical textbook "Essential Cell Biology" by Bruce Alberts et al., red blood cells do contain a small number of mitochondria, but they are primarily used for the production of ATP (adenosine triphosphate) through a process called glycolysis. This ATP is used to maintain the cell's shape and flexibility, as well as to help with other cellular functions. In addition, a study published in Cell Journal by Hilda A. Pickett et al. found that red blood cells also have a small amount of mitochondria to regulate the cell's pH balance by removing excess protons that are produced during the transport of carbon dioxide. This process is essential for maintaining the cell's function and overall health. Furthermore, according to the American Society of Hematology, red blood cells also contain the enzyme carbonic anhydrase, which is responsible for converting carbon dioxide into bicarbonate ions. This process also helps to maintain the cell's pH balance and plays a vital role in the transport of carbon dioxide in the blood. In conclusion, while red blood cells do contain a small amount of mitochondria, it is primarily used for specific functions such as maintaining the cell's shape, regulating pH balance, and aiding in the transport of carbon dioxide. Therefore, the statement that red blood cells have no mitochondria to limit oxygen consumption is false.