Biology Regents Review

Contents: Living Organisms Organelles Human Body Systems Homeostasis in Organisms Genetics Reproduction

Living Organisms:

      Cells are basic units of structure and function in any living thing.

      Metabolism is the sun of all like processes and chemical reactions

      Homeostasis is the maintenance of internal stability regardless of the external environment.  They must be able to respond to stimuli which are changes in the environment.

      Reproduction passes hereditary information to new organisms. It is vital for a species as a whole but not necessary for an individual.

The Life Processes- Living things rely on a variety of specific processes to maintain life.

      Nutrients

      Transport of materials

      Respiration

      Synthesis ( simpleà complex)

      Growth

      Excretion- (egesting)

      Responding to stimuli ( regulation)

      Reproduction

Organic VS Inorganic

      Organic- contain both carbon and hydrogen

      Inorganic doesn’t

Organization

      Cellsà tissuesà organsà organ systemsà organisms

      Organelles- The components of a cell with specific functions in maintenance.

Organelles

      Cytoplasm- transports materials throughout the cell and is the site of many chemical reactions. ( composed mainly of water)

      Nucleus- Large structure that controls the cells metabolism and genetic material. ( brain and control center of the cell)

      Vacuoles- Storage sacks

      Ribosome’s- site of protein synthesis

      Mitochondria- Power house of the cell that contain enzymes that extract energy from nutrients.

      Chloroplasts- Only in plants, they contain chlorophyll and capture light energy to produce food.

      The cell membrane- Thin a structure that surround the cell. Made of lipids and proteins. It serves as a boundary form the outside environment, controls transport of materials into and out of the cell. It also recognizes and responds to chemical signals.

      Passive Transport- Movement of molecules from a place of higher concentration to an area of low concentration. It does not require energy. There are two types of passive transport; diffusion and osmosis. Diffusion is the transport of all substances except for water and Osmosis is transport of water only.

      In cell to cell communication there are two important components; 1. Receptor 2. Message. The receptor determines whether it accepts or rejects the signal. They have the power to block the receptor so that the message can’t go through. These messages are hormones.

Human Body Systems:

      Digestion: a one way passage through the body. It includes the mouth, stomach, intestines, and organs. Food enters the body through the mouth where there is mechanical digestion performed by the teeth, as well as chemical digestion carried out by the saliva. The saliva is composed of salivary amylase which breaks down sugars and starches. The food goes down to the esophagus where there is peristalsis (muscular contraction). The food then enters the stomach where digestion takes place.

      Respiration: The body uses oxygen to break down food molecules to release energy. The function of the respiratory system is the exchange of gases between the blood of the circulatory system and the environment.

      Circulatory system: This process involves movement of materials inside the cell as well of the movement between parts of a multicultural organism. This process transports materials throughout the body. The blood carries food and oxygen to the cells throughout the body. It also carries wastes from the cells to the lungs, kidneys, and skin for excretion. The blood vessels also carry chemical messengers (hormones) and the proteins that attack the foreign substances (antigens) to give the body immunity against antibodies.

      Excretion: this is the removal of all wastes produced by the cells of the body. The human execratory system includes the lungs, kidneys, and sweat glands.

      Movement: movement of the body involves the interaction of muscles and bones (the muscular and skeletal systems.)

      Coordination: the nervous and endocrine system controls and coordinates. Together these systems respond to, and send messages to cells throughout the body. The nervous system sends signals along nerves, and the glands of the endocrine systems produce chemical messengers (hormones) that travel in the blood stream. The brain spinal cord and nerves are part of the nervous system.

      Immunity- The immune system increases the body’s immunity which is its ability to resist disease. Some white blood cells of the immune system engulf and destroy antigens and bacteria. 

      Reproduction- Organisms produce new organisms of the same kind. The two types of reproduction are sexual and asexual. Sexual contains a sperm and an egg where asexual only require one parent.

Homeostasis in organisms

      Photosynthesis- In plants energy for life comes primarily from the sun. Chloroplast contains chlorophyll which captures light. They use the sun energy to convert inorganic molecules to energy. One such is the sugar glucose. As a waste product oxygen is released into the environment.  During cellular respiration plant cells use organic compounds to generate ATP (process of releasing energy in chemical bonds) Glucose is also used to synthesize complex organic compounds.

      Enzymes- Effect the rate of chemical reactions. They also break down the glucose molecules.

      Cellular Respiration- The process in which the energy is released from chemical bonds. Cellular respiration takes place in the mitochondria.

      Gas Exchange- Humans give off to the environment CO2 and the plants give off O2.

      Enzymes are catalysts that affect the rate of chemical reactions. There are many components that affect the enzyme such as:

      Each enzyme is uniquely shaped and has the power to work with one substrate. If the enzyme is deaminated (deformed) than it is no longer reusable. Temperature and the PH affect enzyme activity.

      Dynamic Equilibrium- stability within its limits that  organisms need to maintain

      Feedback mechanism- Involves a cycle in which the output of a system feedbacks to either modify or reinforce the action taken by the system. It helps respond to stimuli. Feedbacks can be positive and negative.

Genetics

      Heredity is the passing of genetic info from one generation to the next through reproduction.

      DNA- heredity information is organized in the form of genes located in chromosomes.  Genesà DNAà Chromosomes

      Methods of reproduction- Asexual reproduction involves one parent or individual. In sexual reproduction there are two parents. Because in asexual there is only one parent the offspring becomes a clone. There are no gametes in asexual reproduction. Sexual reproduction includes the sperm (male) and the egg (female) which are gametes. The offspring receives half of its genetic information from each parent. It includes variations within offspring.

      DNA- a double helix. Each subunit has 3 chemical parts: a 5 carbon sugar, a phosphate group, and nitrogenous base. These babes are represented by the letters A (adenine) G (guanine) C (cytosine) and T (thiamine). A always matches up with T and C always matches up with G.

      Replication produces two identical copies of the cells genetic info each ready to be passed from the parent cell to two offspring cells during cell division.

      RNA- ribonucleic acid. DNA is used as a template to produce RNA. The DNA molecule unzips (not all the way) and nucleic acids line up according to base pairing (uracil replaces thiamine). Messenger RNA and transfer RNA both take part in protein synthesis at the ribosome.

      Mutation- any alteration in the sequence of DNA.

      Selective Breeding- a process in which organism that have more desirable traits are bred with another of that type to concentrate desirable traits.

      Gene Splicing- The cutting of DNA segments in a way that allows the segments to be spliced of moved and attached to the DNA of a new organism.

      Mitosis- produces two cells that have a full set of identical genes and chromosomes. The cells produced as a result are diploid (contain a full set of genetic material).

      Meiosis- Divides the genetic material in a way that results in the production of the sex cells required by organisms that reproduce sexually. Each gamete has only half the genetic material needed for a cell to function properly. ( haploid and monoploid)

      Fertilization- When the sperm and egg combine.

      Zygote- cell that contains all the genetic information needed by the offspring

      Differentiation- In early stages of development the embryos cells undergo differentiation.  Which leads to the formation of specialized cells.

Female reproductive system

      Ovaries- produce egg cells and the hormones estrogen and progesterone. They are located near the open ends of tubes called the oviducts.  The egg cell can be fertilized in the oviduct if sperm are present. The oviducts lead to the uterus where the embryo develops into the fetus.

      Placenta- organ responsible for the passage by diffusion of nutrients and oxygen from the mother’s blood to the fetus. Waste from the fetus diffuses to the mother’s blood.

Male reproductive System

Testes- produce sperm cells and testosterone.

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