Science 9: Biology Test 3 Review PDF

# Science 9: Biology Test 3 Review ## Asexual Reproduction, Sexual Reproduction, Meiosis, Fertilization ### Define Heredity The passage of biological traits or characteristics from parents to offspring through the inheritance of genes. ### Define Traits A genetically determined characteristic or...

# Science 9: Biology Test 3 Review ## Asexual Reproduction, Sexual Reproduction, Meiosis, Fertilization ### Define Heredity The passage of biological traits or characteristics from parents to offspring through the inheritance of genes. ### Define Traits A genetically determined characteristic or condition. They can be physical or behavioral, like eye color or nesting in birds. ### Define Genes A segment of DNA occupying a specific place on a chromosome that is the basic unit of heredity. They determine traits. ### Define Offspring New living things that come from one or more parents. Often called children. ### What does it mean when someone talks about offspring in terms of "nature vs nurture"? * **Nature** is all the parts we get from our parents' genes that make us who we are when we are born. * **Nurture** is the way the world around us acts upon us and changes us as we live and grow. Our nature and our nurture form who we are as individuals. ### Define Asexual Reproduction The formation of identical offspring in the absence of a mate. ## Asexual Reproduction | Type: | Description: | Examples of Organisms that Reproduce this way: | |---|---|---| | Binary Fission (or Mitosis)| The cell replicates its DNA. The cytoplasm elongates and then divides. Two daughter cells form. | one-celled organisms such as: - Bacteria - Protists - Amoebas | | Budding | The parent produces a small bud, or smaller version of itself. The bud either detaches and forms a new individual or stays attached forming a colony. | -Hydra -Yeast -Coral | | Spores | One organism will produce many spores (which act like seeds). They are produced by one parent not the union of two cells. | -Fungi -Moulds -Ferns | | Fragmentation | When a fragment or piece of an organism breaks or is cut off the parent and forms a new individual. | -Starfish -Flatworms (like planaria) -Some plants, ex. pothos and snake plants reproduce via cuttings. | | Vegetative Reproduction (Propagation)| Plant reproduction that does not involve seeds. - fragmentation (cutting) -runners -grafting -tubers -suckers | -Strawberries -Spider plants -Potatoes -Tulips/daffodils -Aspen trees | ## Sexual Reproduction ### Define Sexual Reproduction The reproduction of organisms by the union of male and female reproductive cells (gametes). Genetically varied offspring produced by two parents. ## Advantages and Disadvantages of Asexual and Sexual Reproduction ### Advantages of Asexual Reproduction 1) Large #s of offspring 2) No energy needed to find a mate 3) Little or no parental care 4) Only one organism needed. ### Disadvantages of Asexual Reproduction 1) Offspring are clones (disease or harmful mutation can destroy a large group) 2) Extreme temperatures can wipe out entire colonies. 3) Offspring compete for resources like food and space. ### Advantages of Sexual Reproduction Genetic variation which allows more organisms to survive in changing environments ### Disadvantages of Sexual Reproduction 1) Takes more time (finding a mate, fusion of gametes) 2) Exposure to conditions (disease, predators, harsh environment) when finding a mate 3) Fewer offspring 4) Offspring take longer to mature. 5) Offspring may need to be raised. ## Darwin's Theory of Evolution by Natural Selection In class we talked about Darwin's Finches and how they supported the theory of evolution by natural selection. What do you remember about the theory from class, and how do they support this theory? Darwin's Theory of Evolution by natural selection is when variation in sexual reproduction (sometimes caused by mutations) causes changes to a population by favoring desirable traits, which can create new species. Darwin's Finches from the Galapagos all evolved different traits depending on what island they were on and what they eat (ex: the size and shape of the beak). ### What are gametes? Gametes are sex cells produced by organisms containing half the number of chromosomes in a normal body cell. They are **haploid**. ### In animals: * The male gamete is called **sperm cell**. * The male gamete is produced in the **testes**. * The female gamete is called **ovum/egg cell**. * The female gamete is produced in the **ovaries**. ### In plants: * The male gamete is called **pollen**. * The male gamete is produced in the **anther**. * The female gamete is called **ovum/egg cell**. * The female gamete is produced in the **ovule**. ### The process of producing gametes is called **meiosis**. * **What does haploid mean?** Half the genetic material (n) * **What does diploid mean?** Double the genetic material (2n) * **What is the human haploid number?** 23 * **What is the human diploid number?** 46 * **How many stages are there in meiosis?** 8 divisions w/4 stages each * **What is the result of meiosis?** 4 haploid daughter cells all genetically different. ## The Stages of Meiosis: | Diagram | Stage Name | Description/Key Events | |---|---|---| | [Diagram 1] | **Prophase I** | - Chromosomes condense - Nuclear membrane disappears - Centrides move to opposite poles - Homologous chromosomes pair up and crossing over occurs. | | [Diagram 2] | **Metaphase I** | - Spindle fibers attach to chromosomes - Homologous pairs line up in the middle of the cell (2 lines). | | [Diagram 3] | **Anaphase I** | - Spindle fibers contract bringing homologous chromosomes to opposite poles of the cell. | | [Diagram 4] | **Telophase I (and cytokinesis)** | - Spindle fibers break up. - Nuclear membrane may reform. - Cytokinesis makes two cells. - Reduction division - Cells are now haploid. | ## The Stages of Meiosis II | Diagram | Stage Name | Description/Key Events | |---|---|---| | [Diagram 1] | **Prophase II** | - Centrioles will move to opposite sides. - Spindle fibers reattach. | | [Diagram 2] | **Metaphase II** | - Spindle fibers line up chromosomes in the middle of the cell in single file. | | [Diagram 3] | **Anaphase II** | - Spindle fibers contract and move sister chromatids to opposite poles of the cell. | | [Diagram 4] | **Telophase II (and cytokinesis)** | - Nuclear membrane reforms. - Spindle fibers disappear - Chromosomes decondense. - 2 cells split into 4 cells. (4 haploid cells become 4 haploid cells) | ## Compare and Contrast Mitosis and Meiosis [Diagram] ## Mitosis * PMAT happens once * Important for growth and repair * Process ends with 2 identical cells, both diploid * Crossing over never occurs. * Mitosis is a cycle ## Meiosis * PMAT happens twice * Needed to make gametes * Interphase occurs once before each process begins. * Process ends with 4 different cells, all haploid. * In prophase I crossing over occurs. * Meiosis is NOT a cycle ### Define Fertilization When male and female gametes combine and their nuclei fuse together to form one singular cell. ## Diagram 1: The Process of Fertilization in Humans [Diagram] * Maternal chromosome * Paternal chromosome * Sperm cell (haploid) * Zygote (diploid) * Egg cell/ovum (haploid) #### **Explain the process of fertilization in humans:** 1. The sperm meets the egg in the fallopian tube of the female reproductive system. 2. The head of the sperm reacts with the cell membrane of the egg and starts to break it down. 3. Their cell membranes fuse and the nucleus of the sperm enters the egg. 4. The egg's membrane becomes hard so no other sperm can enter. 5. The nucleus of the egg and sperm combine to make a diploid nucleus that forms the zygote. ## Diagram 2: The Development of a Zygote [Diagram] * Zygote (fertilized egg) * Early cleavage * Blastocyst * Late blastocyst * Fertilization * Fallopian tube * Uterine tube * Secondary oocyte * Ovulation * Uterus * Endometrium * Ovary #### **Word Bank:** Fertilization, fallopian tube, ovary, uterus #### **Define Self-pollination:** When pollen arrives on the stigma of a flower from the same plant. #### **Define Cross-pollination:** When pollen lands on the stigma of a flower from a different plant (but the same kind of plant). #### **How are plants pollinated?** 1. **Wind:** Blown by the wind 2. **Water:** Carried by rain 3. **Insects:** (Bees, butterflies, moths, etc.) - Carried on their bodies. 4. **Animals:** (Hummingbirds, dogs, deer, etc.) - Carried on their bodies. ## Diagram 3: A Flower [Diagram] * **Stigma** * **Style** * **Anther** * **Filament** * **Stamen** * **Pistil** * **Petal** * **Sepal** * **Ovule** #### **Word bank:** anther, filament, ovary, petal, pistil, stamen, stigma, stile #### **How do plants form seeds?** 1. **Pollination:** Pollen grains must transfer to the stigma. 2. **Germination:** Pollen tube grows toward the egg cell. 3. **Penetration:** Pollen tube makes it all the way down the style to th ovule. 4. **Fertilization:** The nuclei of the pollen grain and the ovule fuse. 5. **The fertilized ovule then forms a SEED!**