Biology PDF Past Paper

Biology - 1 ‫بدون تصنيف‬١٨:٥٧ ‫ الساعة‬،‫اليوم‬ Biology - 1 1. **Why did Aristotle classify living organisms as either plants or animals?** - Aristotle observed fundamental differences between organisms and used this basis to group them logically. 2. **What is the significance of Carolus Li...

Biology - 1 ‫بدون تصنيف‬١٨:٥٧ ‫ الساعة‬،‫اليوم‬ Biology - 1 1. **Why did Aristotle classify living organisms as either plants or animals?** - Aristotle observed fundamental differences between organisms and used this basis to group them logically. 2. **What is the significance of Carolus Linnaeus in taxonomy?** - Carolus Linnaeus developed the system of binomial nomenclature, providing a standardized method to name and classify organisms. 3. **What are the three domains proposed by Carl Woese, and how are they distinct?** - The three domains are Bacteria, Archaea, and Eukarya. Bacteria and Archaea are both prokaryotes but differ in their DNA sequences and biochemical properties. Eukarya includes all eukaryotic organisms. 4. **Why is it important for scientists to assign scientific names to organisms?** - Scientific names prevent confusion caused by common names and provide a universal method to identify and classify organisms. 5. **Explain the rules for writing scientific names according to binomial nomenclature.** - Scientific names are written in Latin, with the genus capitalized and the species lowercase. Both names are either italicized or underlined. 6. **What is the main purpose of classifying organisms?** - To study the diversity of life, organize and name organisms, and provide a system to identify and understand relationships among species. 7. **What is the modern system of classification based on?** - Modern classification is based on evolutionary descent and genetic similarities, using DNA and RNA comparisons to determine relationships. 8. **What distinguishes the Kingdom Archaebacteria from the Kingdom Eubacteria?** - Archaebacteria are found in extreme environments and have distinct genetic sequences from Eubacteria, which are more common bacteria found in various environments. 9. **Describe the characteristics of organisms in the Kingdom Protista.** - Kingdom Protista includes mostly unicellular eukaryotes that can be autotrophic or heterotrophic. Examples are amoebas, paramecia, and euglenas. 10. **What are the primary characteristics of organisms in the Kingdom Fungi?** - Fungi are mostly multicellular eukaryotes that are heterotrophic decomposers, such as mushrooms, yeasts, mildews, and molds. 11. **What is the importance of common structures, embryology, and DNA in classifying organisms?** - Common structures, embryology, and DNA help scientists determine relationships among organisms and classify them based on evolutionary descent. 12. **How many species have biologists identified and named so far, and how many do they estimate remain unidentified?** - Biologists have identified and named approximately 1.5 million species, and they estimate that between 2 and 100 million species have yet to be identified. 13. **What are the six kingdoms in the modern classification system?** - The six kingdoms are Archaebacteria, Eubacteria, Protista, Fungi, Plantae, and Animalia. 14. **Why was the kingdom Monera divided into two separate kingdoms?** - The kingdom Monera was divided into Archaebacteria and Eubacteria due to significant differences in their DNA sequences and biochemical properties. 15. **What are the characteristics of organisms in the Kingdom Plantae?** - Organisms in the Kingdom Plantae are multicellular eukaryotes that are autotrophic, meaning they produce their own food through photosynthesis. Examples include mosses, ferns,‫ ؛‬conifers, and flowering plants. 16. **What are the characteristics of organisms in the Kingdom Animalia?**  - Organisms in the Kingdom Animalia are multicellular eukaryotes that are heterotrophic, meaning they obtain food by consuming other organisms. Examples include sponges, worms, insects, fish, and mammals. 17. **Explain the hierarchical levels of classification from the most specific to the least specific.** - The hierarchical levels of classification are species, genus, family, order, class, phylum, and kingdom, with species being the most specific and kingdom the least specific. 18. **How do similarities and differences in DNA and RNA contribute to modern classification?** - Scientists use similarities and differences in DNA and RNA sequences to determine evolutionary relationships and classify organisms into appropriate groups. 19. **What is the binomial name of the polar bear, and what do its genus and species names indicate?** - The binomial name of the polar bear is Ursus maritimus. The genus name Ursus indicates it is a bear, and the species name maritimus describes its habitat on pack ice floating on the sea. 20. **Describe the type of environment where Archaebacteria are typically found.** - Archaebacteria are typically found in extreme environments such as volcanoes, deep-sea vents, and hot springs. 21. **What is the significance of using Latin and Greek for scientific names?** - Latin and Greek are used for scientific names because these languages are unchanging and universally understood among scientists. 22. **What is the main difference between autotrophs and heterotrophs?** - Autotrophs produce their own food through processes like photosynthesis, while heterotrophs obtain their food by consuming other organisms. 23. **Give an example of an organism from each of the six kingdoms.** - Archaebacteria: Methanogens - Eubacteria: Escherichia coli (E. coli) - Protista: Amoeba - Fungi: Mushroom - Plantae: Sunflower - Animalia: Jellyfish 24. **Why do scientists use a classification system to name and group organisms?** - Scientists use a classification system to name and group organisms to organize biological diversity logically and consistently, making it easier to study and understand relationships among species. 25. **What is the common name and scientific name of the Florida panther?** - The common names of the Florida panther are Florida panther, mountain lion, puma, and cougar. Its scientific name is Felis concolor. Biology - 2 1. **What is taxonomy?** - **Answer:** Taxonomy is the science of classifying living organisms into groups based on shared characteristics. 2. **What is the Linnaean hierarchy?** - **Answer:** The Linnaean hierarchy is a system of classifying organisms into a hierarchy of categories such as Kingdom, Phylum, Class, Order, Family, Genus, and Species. 3. **What is binomial nomenclature?** - **Answer:** Binomial nomenclature is a system for naming species where each species is given a two-part name: the first part is the genus (capitalized) and the second part is the species (not capitalized), both written in italics, e.g., *Homo sapiens*. 4. **What are the three domains of life in the new classification system?** - **Answer:** The three domains of life are Bacteria, Archaea, and Eukarya. 5. **What distinguishes Archaea from Bacteria?** - **Answer:** Archaea differ from Bacteria in their DNA sequence and certain biochemical properties, making them more similar to eukaryotes in some aspects. 6. **What are the characteristics of the Kingdom Protista?** - **Answer:** Protists are mostly unicellular organisms, possess specialized organelles, may have cell walls, can move using flagella, cilia, or pseudopodia, and reproduce both asexually and sexually. 7. **What are the two subkingdoms of Kingdom Animalia and their characteristics?** - **Answer:** The two subkingdoms are Parazoa (organisms without definite body layers, e.g., sponges) and Metazoa (organisms with definite body layers, including tissues and organs). 8. **What is the difference between radial and bilateral symmetry in animals?** - **Answer:** Radial symmetry means the body parts radiate from the center and can be divided into mirror images by multiple planes. Bilateral symmetry means the body has a left and right side, and only one plane can divide it into mirror-image halves. 9. **What are the three embryonic germ layers in triploblastic animals?** - **Answer:** The three embryonic germ layers in triploblastic animals are ectoderm, mesoderm, and endoderm. 10. **What are the main criteria used to classify animals into different phyla within the subkingdom Metazoa?** - **Answer:** The main criteria include body symmetry, the number of embryonic germ layers, the presence of an internal body cavity, and the presence of a backbone. 11. **What is the significance of scientific names in taxonomy?** - **Answer:** Scientific names avoid confusion caused by common names, ensuring that each organism has a unique, universally recognized name. 12. **What is the key characteristic that distinguishes prokaryotic cells from eukaryotic cells?** - **Answer:** Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have both. 13. **Name the kingdoms classified under the domain Eukarya.** - **Answer:** The kingdoms under Eukarya are Animalia, Plantae, Fungi, Protista, Archaebacteria, and Eubacteria. 14. **Describe the contractile vacuole function in Protists.** - **Answer:** The contractile vacuole in Protists helps in osmoregulation by controlling excess water and maintaining osmotic pressure within the cell. 15. **What are the different modes of movement in Protists?** - **Answer:** Protists move using flagella, cilia, or pseudopodia; some are sessile (non-motile). 16. **How do most Protists reproduce?** - **Answer:** Most Protists reproduce asexually by mitosis, budding, or schizogony, though some also have an obligate sexual reproductive phase through conjugation. 17. **Give an example of an animal-like protist and its characteristics.** - **Answer:** *Trypanosoma* is an animal-like protist that moves by flagella, is a hemoflagellate (blood parasite), and causes diseases like African sleeping sickness. 18. **What are the main characteristics of the Kingdom Animalia?** - **Answer:** Animals are multicellular, lack cell walls, have specialized tissues and organs, are heterotrophic, capable of locomotion, and store glycogen and fat. 19. **What are the differences between Parazoa and Metazoa?** - **Answer:** Parazoa, like sponges, lack definite body layers and tissues, while Metazoa have distinct tissues and organs derived from embryonic layers. 20. **Explain the significance of the domain in the new classification system.** - **Answer:** The domain is a higher taxonomic level than the kingdom, grouping organisms based on fundamental differences in cell type and molecular biology. 21. **What are the three types of body cavities in triploblastic animals?** - **Answer:** Triploblastic animals can be acoelomate (no body cavity), pseudocoelomate (body cavity partially lined with mesoderm), or coelomate (body cavity fully lined with mesoderm). 22. **Name a disease caused by Plasmodium and its mode of transmission.**  - **Answer:** Malaria is caused by Plasmodium and is transmitted by the bite of an infected female Anopheles mosquito. 23. **What role do cilia play in the movement of certain protists?** - **Answer:** Cilia are tiny, hair-like structures that beat in coordinated waves to propel the protist through water. 24. **What is the primary mode of nutrition for fungi in the Kingdom Eukarya?** - **Answer:** Fungi are heterotrophic, primarily obtaining nutrients through absorption by decomposing organic matter. 25. **How do sponges in the phylum Porifera differ from other animals?** - **Answer:** Sponges lack true tissues and organs, have a porous body, and rely on a water flow system for feeding and respiration. 26. **What are some examples of organisms in the kingdom Plantae?** - **Answer:** Examples include trees, shrubs, grasses, ferns, and mosses. 27. **How do members of the kingdom Fungi reproduce?** - **Answer:** Fungi reproduce through both asexual methods (spores, budding) and sexual methods (fusion of hyphae, spore formation). 28. **What is the main habitat for most protists?** - **Answer:** Most protists are found in freshwater environments, though some inhabit marine, soil, or parasitic environments. 29. **What distinguishes a species within a genus?** - **Answer:** A species is a group of organisms capable of interbreeding and producing fertile offspring, distinguished by unique characteristics within a genus. 30. **Describe the process of binary fission in protists.** - **Answer:** Binary fission is a form of asexual reproduction where a single organism divides into two identical daughter cells. Biology - 3 1. **What is the basic structural and functional unit of all living organisms?** - The cell. 2. **What is the smallest unit of an organism that is classified as living?** - The cell. 3. **What are unicellular organisms?** - Organisms that consist of a single cell. 4. **Give an example of a unicellular organism.** - Most bacteria. 5. **What are multicellular organisms?** - Organisms composed of more than one cell. 6. **What is the largest known cell?** - An unfertilized ostrich egg cell. 7. **What are the three main points of cell theory?** - 1) The cell is the basic unit of organization, 2) Organisms are composed of one or more cells, 3) New cells come from old cells. 8. **What is cellular differentiation?** - Specialization of cell structure and function. 9. **What are prokaryotic cells?** - Cells without a nucleus and other membrane-bound organelles. 10. **What are the three regions of a prokaryotic cell?**  - Flagella and projections, cell envelope, and the interior containing DNA. 11. **What is the function of the cell envelope in prokaryotes?** - Provides rigidity, protects the cell, and acts as a filter. 12. **What type of DNA is found in prokaryotic cells?** - Circular DNA molecules. 13. **What is a plasmid?** - Extrachromosomal DNA elements that carry additional functions like antibiotic resistance. 14. **What are eukaryotic cells?** - Cells with a nucleus and other membrane-bound organelles. 15. **What distinguishes eukaryotic cells from prokaryotic cells?** - Presence of a nucleus, more complex structures, and organelles like mitochondria. 16. **What is the function of cilia in eukaryotic cells?** - Sensation and coordination of cellular signaling pathways. 17. **What are the three main constituents of human cells?** - Plasma membrane, cytoplasm, and nucleus. 18. **What is the structure of the plasma membrane?** - Phospholipid bilayer with cholesterol, proteins, and carbohydrates. 19. **List two functions of the plasma membrane.** - Communication and selective permeability. 20. **What is cytoplasm composed of?** - Cytosol, inclusions, and organelles. ‫ي‬ 21. **What is the function of the cytoplasm?** - Site of metabolic processes and storage of nutrients. 22. **What is the structure of the nucleus?** - Surrounded by a double membrane and contains nucleolus and chromatin. 23. **What are ribosomes?** - Dense cytoplasmic granules that synthesize proteins. 24. **What is the function of the rough endoplasmic reticulum?** - Synthesizes proteins for secretion and lysosomal enzymes. 25. **What is the function of the smooth endoplasmic reticulum?** - Synthesizes lipids and detoxifies drugs. 26. **What is the Golgi apparatus?** - Stacked series of flattened membrane sacs that modify and sort proteins. 27. **What is the function of lysosomes?** - Digest materials ingested by the cell and remove old organelles. 28. **What are peroxisomes?** - Membrane-enclosed sacs that break down harmful substances. 29. **What is the function of mitochondria?** - Synthesize ATP during cellular respiration. 30. **What is the role of the cytoskeleton?** - Provides structural support and facilitates cellular movement. 31. **What is the function of the nucleolus?** - Site of ribosome subunit assembly. 32. **What is chromatin?** - The material that makes up chromosomes, consisting of DNA and proteins. 33. **What are membrane-bound organelles?** - Organelles surrounded by membranes, such as the ER, Golgi apparatus, lysosomes, peroxisomes, and mitochondria. 34. **What is the function of the smooth endoplasmic reticulum (smooth ER)?** - Synthesizes lipids, metabolizes carbohydrates, and detoxifies drugs. 35. **What is the difference between the smooth ER and rough ER?** - The rough ER has ribosomes attached to its surface, whereas the smooth ER does not. 36. **What is the function of the Golgi apparatus?** - Modifies, packages, and sorts proteins for secretion or inclusion in the plasma membrane. 37. **What is autolysis?** - The self-destruction of a cell through the action of its own enzymes, often seen in lysosomes. 38. **What is the function of peroxisomes?** - Convert hydrogen peroxide into water and detoxify harmful substances. 39. **What are mitochondria known as and why?** - The powerhouses of the cell because they synthesize most of the ATP. 40. **What is the structure of ribosomes?** - Dense cytoplasmic granules with two subunits, which can be free in the cytoplasm or attached to the rough ER. 41. **What is the function of the cytoskeleton?** - Provides structural support and facilitates movement within the cell. 42. **What are microfilaments?** - Actin protein monomers that maintain cell shape and aid in muscle contraction and cell movement. 43. **What are intermediate filaments?** - Protein components that provide structural support and stabilize cell junctions. 44. **What are microtubules?** - Hollow cylinders of tubulin protein that support cell shape, hold organelles in place, and facilitate movement. 45. **What is the function of the centrosome?** - Organizes microtubules and participates in spindle formation during cell division. 46. **What is the role of cilia?** - Move fluid, mucus, and materials over the cell surface. 47. **What is the function of a flagellum?** - Propels sperm cells in human males. 48. **What are microvilli?** - Membrane folds that increase the surface area for absorption and secretion. 49. **What are the four principal types of tissues in the body?** - Epithelial tissue, connective tissue, muscle tissue, and nervous tissue. 50. **What is the function of epithelial tissue?** - Provides protection and facilitates absorption and secretion. 51. **What is the function of connective tissue?** - Supports and binds other tissues and organs. 52. **What is the role of muscle tissue?** - Facilitates body movement. 53. **What is the function of nervous tissue?** - Transmits nerve impulses and processes information. 54. **What does the plasma membrane's selective permeability regulate?** - Entry and exit of ions, nutrients, and waste molecules. 55. **What is the function of the cytosol?** - Provides support for organelles and serves as a medium for diffusion. 56. **What are organelles?** - Tiny structures within the cell that perform specific functions. 57. **What are inclusions?** - Nonfunctional temporary structures that store cellular products. 58. **What are melanin granules?** - Inclusions that store pigment in cells. 59. **What is glycogen stored as in cells?** - Glycogen granules. 60. **What are the main components of the plasma membrane?** - Phospholipids, cholesterol, proteins, and carbohydrates.