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Science 09 - Biology Cheat Sheet (DRAFT) by

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Advantages & Disadv­antages - Asexual Reprod­uction

Advantages - many offsprings produced quickly when conditions are favourable and ensure species may survive when conditions or # of predators change, little energy required to find a mate, large colonies can form to out-co­mpete other organisms for nutrients & water
Disadv­antages - negative mutation can make offspring suscep­tible to disease, can destroy large # of offspring, some ways produce offspring close together = competing for food and space, unfavo­urable conditions (extreme temper­ature) can wipe out entire colony


DNA - a molecule that stores the genetic inform­ation of an organism, 4 nitrogen bases (adenine, guanine, cytosine, thymine)
States of DNA of increasing compac­tness - uncoiled double helix, chromatin, chromo­somes
Contains the instru­ctions for a cell to function


Proteins are not made here, activities carried out form here can be studied using nanote­chn­ology, DNA of eukaryotic cells found here
Cytoplasm & duplicated organelles divide during cytoki­nesis, duplicated contents in cell’s nucleus divides during mitosis

Binary Fission

Binary Fission - reprod­uction of prokar­yotic cells (w/out nucleus), into 2 daughter cells after DNA replic­ation, no cell cycle & mitosis

Vegetative Fragme­ntation

Fragme­ntation - if an organism breaks apart from injury, each fragment develops into a clone of its parent

Vegetative Reprod­uction

Reprod­uction - special cells (usually in plant stems or roots divide repeatedly to from structure that will develop into an identical plant to parent
Disadv­antages - new plants grow closely to each other and parent, can lead to compet­ition for soil, nutrients and light - less healthy plants


Cloning - technology used in agricu­lture and research to copy desired organisms, tissues, genes
cloning that produces genetic duplicate of cells, tissues, organisms, for correcting health problems

Reprod­uctive Cloning

Reprod­uctive Cloning - produces a genetic duplicate of existing or dead organisms through somatic cell nuclear transfer, requires stem cells
1: remove nucleus from egg cell 2: remove mammary gland cell from adult female 3: fuse mammary & egg cell w/ electr­icity 4: fused cell begins dividing 5: insert dividing embryo into a surrogate female's uterus
contro­versial since best stem cells are form embryos which are destroyed when harvesting cells

Stem Cells

Stem Cells - a cell that can become­/pr­oduce different kinds of cells by differ­ent­iation, can be used to replace damaged cells from injuries or disease


Checkp­oints - prevent division if cell's out of nutrients, DNA not replicated or is damaged

Gene Mutation

Gene Mutation - results in the death of an organism, substi­tution, addition, deletion can occur during DNA replic­ation or when chromo­somes fail to move into 2 cells , proteins' effect on the organism may be positive, negative, or neutral, if involved checkp­oints = out of control cell cycle = cancer
Genes = segments of DNA, located on chromo­somes

Cancer Cells

Cancer cells - damaged cells may replicate unchecked, generally is the result of mutation, cancer doesn't result from cells that don't have adequate nutrients

Chromosome Mutation

Chromosome Mutation - occurs randomly & naturally or because of mutagens (radia­tion, chemic­als), can lead to genetic disease or death, changes in chromo­somes can cause changes in Genetic Inform­ati­on(­during meiosis), can be passed on to an offspring

Whole Chromo­somes Mutation

Whole Chromosome Mutation - can occur in meiosis I when homologous chromo­somes fail to separate or when sister chromatids fail to separate in meiosis II
Result: 1 gamete will have 2 copies and i will have 0, zygotes rarely survive w/ the result if they do = serious genetic disorder

Advantages & Disadv­antages - Sexual Reprod­uction

Advantages - offspring are geneti­cally different form their parents, may survive new diseases or other threats appeared in a popula­tion, more protection to embryo and more parental care to offspring, sperm are deposited inside the female (inter­nal), little energy required to fins a mate and great # of offsprings can repopulate an area after a disaster (external)
Disadv­antages - fewer offspring produced, if # of predators increase, population will decline, more energy to find a mate and may expose indivi­duals to predators, diseases, or harsh enviro­nmental conditions (inter­nal), gametes, embryos, and offsprings unprot­ected and often are preyed upon (external)