2024-2025 7G Science Revision PDF

A logo of a foreign language Description automatically generated **1^st^ SEMESTER REVIEW SHEET - ACADEMIC YEAR 2024 - 2025** ***Subject: SCIENCE -- GRADE 7G*** *Student name:.................................................................... Class:......................* ***Chapter 4: Reproduct...

A logo of a foreign language Description automatically generated **1^st^ SEMESTER REVIEW SHEET - ACADEMIC YEAR 2024 - 2025** ***Subject: SCIENCE -- GRADE 7G*** *Student name:.................................................................... Class:......................* ***Chapter 4: Reproduction of Organisms*** ========================================== SEXUAL REPRODUCTION AND MEIOSIS - Sexual Reproduction: a type of reproduction in which the genetic material from two different cells combine, producing an offspring. - Egg cell: female sex cell - Sperm cell: male sex cell - Fertilization: sperm cells and egg cell join together - Zygote: fertilized cell - Homologous chromosomes: pairs of chromosomes that have genes for the same traits arranged in the same order - Diploid cell: cells that have pair of chromosomes - Haploid cell: cells that have only one chromosome from each pair - Meiosis: one diploid cell divides and makes four haploid sex cells - Phases of Meiosis:  - Mitosis versus Meiosis A table with text on it Description automatically generated - Advantages of Sexual Reproduction - Genetic variation: organisms can develop traits that might help them survive in a harsh environment - Selective breeding: used to develop many plants and animals with desirable traits - Disadvantages of Sexual Reproduction - Takes time and energy: organisms need to grow and develop for it to produce sex cells - Reproduction cannot take place without a mate: finding a mate takes time ASEXUAL REPRODUCTION - Asexual Reproduction: one parent organism produces offspring without meiosis and fertilization - Types of Asexual Reproduction - Fission: cell division in prokaryotes that form two genetically identical cells - Budding: a new organism grows by mitosis and cell division on the body of its parent - Animal Regeneration: occurs when an offspring grows from a piece of its parent - Vegetative Reproduction: offspring grows from a part of its parent plant - Cloning: type of asexual reproduction performed in a laboratory that produces identical individuals from a cell or from a cluster of cells. - Sperm cell: male sex cell - Fertilization: sperm cells and egg cells join together - Advantages of Asexual Reproduction - Can reproduce without a mate - Can reproduce a large number of offspring - Disadvantages of Asexual Reproduction - Genetic mutation - Lacks genetic variation ***Chapter 5: Genetics*** ========================= MENDEL AND HIS PEAS - Heredity: passing of traits from parents to offspring - Genetics: study of how traits are passed from parents to offspring - Gregor Mendel: disprove blending inheritance and became the Father of Genetics - Blending Inheritance: organism's characteristics or traits mixed like colors of paint because offspring resembled both parents - Mendel's Experimental Method: studied genetics by doing controlled breeding experiments with pea plants - Types of Pollination: - Self-pollination: pollen from one plant lands on the pistil of a flower of the same plant - Cross pollination: when wind, water, or animals carry pollen from one pollen to another - True-Breeding Plants: always produce offspring with traits that match the parent - Hybrid Plants: came from true-breeding plants with different forms of different traits - Two Genetic Factors that controlled each Inherited trait: - Dominant trait: genetic factor that block another genetic factor - Recessive trait: genetic factor that is blocked by the presence of dominant factor UNDERSTANDING INHERITANCE - Gene: contains the genetic information from each trait - Allele: different forms of gene - Two important genetic ratio are: - Phenotype: how a trait appears or expressed - Genotype: two alleles that control the phenotype of a trait - Homozygous: two alleles of the gene are the same (RR or rr) - Heterozygous: two alleles of the gene are different (Rr) - Punnett square: model used to predict possible genotypes and phenotypes of offspring - Pedigree: shows phenotypes and genotypes of genetically related family - Complex Pattern of Inheritance - Incomplete dominance: when the offspring's phenotype is a combination of the parent's phenotype - Codominance: both alleles can be observed in a phenotype - Multiple allele: genes that have more than two alleles - Polygenic inheritance: multiple genes determine the phenotype of the trait DNA AND GENETICS - DNA (deoxyribonucleic acid): contains the genetic information - Double helix structure: model of the DNA - James Watson and Francis Crick: build the model of the DNA - Nucleotides: molecules made of nitrogen base, sugar, and phosphate group Four Nitrogen bases - - Cytosine - Guanine - Adenosine - Thymine - - Replication: process of copying DNA molecules from another DNA molecule - DNA Replication  - Transcription: process of making mRNA from DNA - RNA (ribonucleic acid): carries the code of making proteins from nucleus to cytoplasm - Gene Mutation: change in the nucleotide sequence of the gene A diagram of a dna structure Description automatically generated ***Chapter 6: The Environment and Change Over Time*** ===================================================== FOSSIL EVIDENCE OF EVOLUTION - Fossils: remains or evidence of once-living organisms - Fossil Record: made up of all the fossils that have ever discovered on Earth - Fossil Formation: *Mineralization* minerals replace the organism's original material and harden into a rock ------------------- -------------------------------------------------------------------------------------------------------- *Carbonization* when a dead organism is compressed over time and pressure drives off its liquids and gases *Mold and Cast* impression of an organism in a rock is called mold and cast is a fossil copy of an organism in a rock. *Trace fossils* preserved evidence of the activity of an organism *Original Matter* preserved original tissues of an organism - Determining Fossils Age *Relative-age dating* scientists determine the relative order in which rock layers are deposited ----------------------- -------------------------------------------------------------------------------------------------- *Absolute-age dating* scientists measure the ratio of unstable isotopes to stable isotopes to find the age of the rock - Geologic Time Scale: chart that divides the Earth's history into different time units - Extinction: occurs when the last individual organism of a species dies - Cause of Extinction - Sudden Environment Change: volcanic eruption - Gradual Environmental Change: movement of tectonic plates - Biological Evolution: change over time of population of related organism THEORY OF EVOLUTION BY NATURAL SELECTION - Charles Darwin: English naturalist who developed the theory of Evolution - Naturalist: person who studies plants and animals by observing them - Darwin's Theory: *Common Ancestor* The tortoise shared a common ancestor. Darwin suspected that a storm carried a small ancestral population to the island. --------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ *Variation* A slight difference in an inherited trait of individual members of a species. *Natural Selection* Process by which populations of organisms variations that help them survive in their environments live longer, compete better, and reproduce more than those who do not have variations. - Adaptation: inherited trait that increases an organism's chance of surviving and reproducing in its environment - Types of Adaptation: - Structural: color, shape and other physical characteristics - Behavioral: way an organism behaves or acts - Functional: involves internal body systems that affect biochemistry - Environmental Interactions - Mimicry: resemblance of one species to another species - Camouflage: enables the species to blend in its environment - Selective Breeding: breeding of organisms for desired characteristics BIOLOGICAL EVIDENCE OF EVOLUTION - Comparative Anatomy: study of similarities and differences among structures of living species - Homologous Structure: body parts of organisms that are similar in structure and position but different in function - Analogous Structure: body parts that perform a similar function but differ in structure - Vestigial Structure: body parts that have lost their original function through evolution - Embryology: science of the development of embryos from fertilization to birth - Molecular Biology: study of gene structure and function 1. Differentiate Sexual Reproduction from Asexual Reproduction 2. Explain the stages of Meiosis. 3. Differentiate haploid cell from diploid cell 4. What are the advantages and disadvantages of sexual reproduction? 5. What are the advantages and disadvantages of asexual reproduction? 6. Differentiate recessive and dominant trait. 7. What kind of pollination did Mendel use in his experiments and how did he do it? 8. What's the difference between codominance and incomplete dominance? 9. How does replication happen? 10. How are fossils formed during mineralization? 11. Give 2 examples of causes of Extinction. 12. Birds migrating from one place to another is an example of what kind of adaptation? 13. Differentiate mimicry from camouflage. 14. Why do people do selective breeding in some animals? 15. Differentiate meiosis and mitosis. 16. Draw and differentiate the different kinds of gene mutations. **THE END.**