Science 9 Unit 1

Sustainability Ability of the Environment and living things it supports to endure into the future Reproduction The production of offspring (sexual or asexual) Continuity How each species of organism continues to exist over time Asexual reproduction Needs only 1 parent and produces genetically identical offspring Sexual reproduction Needs 2 parents and produces genetically different offspring DNA (Deoxyribonucleic acid) Stores genetic information of an organism Structure of DNA Two long strands shaped like a twisted ladder containing 4 kinds of chemical building blocks called nucleotides Binary fission Type of asexual reproduction where a parent cell splits into two separate, identical cells, called daughter cells Cell cycle The process by which all eukaryotic cells reproduce Mitosis The process of cell division that includes stages: Interphase, Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis Cytokinesis The division of the cytoplasm and organelles to form two separate cells Meiosis The process that turns diploid cells into haploid cells for reproduction Gamete A haploid cell that is involved in sexual reproduction Diploid A cell that contains two complete sets of chromosomes, one from each parent (46 chromosomes in humans) Haploid A cell that contains one complete set of chromosomes (23 chromosomes in humans) Fertilization The process that occurs when male sperm cells combine with female egg cells Homologous pair A pair of chromosomes that carry almost identical information, one from each parent Crossing over The exchange of genetic material between homologous chromosomes during Prophase I of meiosis Independent assortment The random arrangement of chromosome pairs during Metaphase I of meiosis Asexual reproduction advantages Only 1 parent is needed, reproduction occurs fast, offspring are genetically identical to the parent Asexual reproduction disadvantages Lack of genetic diversity, vulnerable to changes in environment Sexual reproduction advantages Genetic variation/diversity, allows some individuals to survive if environment changes Sexual reproduction disadvantages Searching for a mate takes time, fewer offspring are produced, takes longer to grow and reproduce Yeast reproduction Yeast cell grows a bud that pinches off to become its own cell Mould reproduction Moulds form spores that are genetically identical to the cells they come from Plant reproduction Plants can reproduce sexually and asexually, with asexual reproduction involving vegetative propagation