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ESO 3. Biology and Geology

Topic 1.  Levels of Organisation in Living Beings

Living beings are formed by clusters of matter increasingly bigger and complex. These clusters of matter are classified in levels: every new level is more complex than the previous one. The simplest organisms (bacteria, protozoa, unicellular algae and yeasts) only reach the cellular level, but the more sofisticated ones also have tissues, organs and systems of organs.

Examples
BioelementsC, H, O, N, P, S
BiomoleculesCarbohydrates, proteins, lipids, vitamins, nucleic acids, water, mineral salts
CellsSperm cell, palisade cell, muscular cell, neurone…
TissuesMuscle tissue, nerve tissue, blood…
OrgansBrachial biceps, heart, brain, leaf, root…
Systems of organsDigestive system, nervous system, circulatory system, skeleton…
ApparatusMotor apparatus
Multicellular organismA person, a cat, a fungus, a black poplar…
Topic 1.  Bioelements and Biomolecules

The bioelements are most abundant chemical elements in a livig being, which are not much the same ones that you can find in a rock or in the air. The top six are C, H, O, N, P, S, and they're called primary bioelements.

The molecules that can be found in all living beings, from the simplest bacterium to the most complex animal, are called biomolecules, the molecules of Life. There are two types:

  • Organic: Carbohydrates, proteins, lipids, vitamins and nucleic acids. They all have an inner skeleton built mainly with carbon atoms, which allows for a really large size. The organic biomolecules can only be produced by living beings, if we discard artificial synthesis. This is, they can not be produced by geological or atmospheric processes, for instance.
  • Inorganic: Water and mineral salts. They don't have an inner skeleton of carbon atoms and can be produced in non-biological processes.
Topic 1.  Cells

All living beings are made up of complex structures called cells. Cells are made up of billions of biomolecules working together. Viruses are not regarded as living beings because they are not made up of cells.

Living beings can be (a) unicellular: made up of just one cell (bacteria, protozoa, many algae, yeasts); and (b) multicellular: made up of more than one cell: (some algae, most fungi, plants and animals).

All cells are able to perform the three vital functions: (a) they reproduce, quite usually by mitosis, a process that yields two daughter cells with almost identical genetic material; (b) they interact with their environment, giving responses to specific stimuli, as when a white blood cell is able to detect and destroy a bacterium; and (c) they feed, meaning that they are able to exchange matter and energy with their environment, as when a human cell takes oxygen from the blood and releases carbon dioxide.

All the cells have (a) a cell membrane, which is the cellular envelope, (b) a cytoplasm with organelles, which are specialized cell compartments where specific functions are fulfilled, and (c) genetic material, that carries the instructions that allow both the cellular work and its self-construction.

There are two main kinds of cells: (a) the cells of the bacteria and archaea have no real nucleus: they are said to be prokaryotic; (b) the cells of all the other living beings (algae, protozoa, fungi, plants and animals) have their genetic material separated from the cytoplasm by a nuclear membrane: they are said to be eukaryotic.

The cells of the plants can be easily distinguished from those of the animals because (a) they have a semi-rigid cell wall, made of cellulose, surrounding the cell membrane, that usually gives the cell a polyhedral shape; (b) they have one kind of organelles, called chloroplasts, where sunlight energy is used to start building their own organic substances through a chemical process called photosynthesis; (c) they use to have one or a few big vacuoles that contain sap (instead of lots of smaller ones without sap) which normally push the nucleus out to the periphery of the cell; and (d) although they have equivalent structures, they lack centrosomes, the organelles that control the arrangement of the chromosomes during mitosis in an animal cell.

Topic 1.  Common Structures in Eukaryotic Cells
Description Function Where
Cell wall Outermost layer of a plant cell composed of cellulose and other complex carbohydrates. Helps to support and protect the cell. P
Flagella (flagellum) Long and scarce threadlike structures that extend from the surface of the cell. Used for movement of the cell or to move fluids over the cell's surface for absorption. A
Cilia (cilium) Short and abundant threadlike structures that extend from the surface of the cell. Used for movement of the cell or to move fluids over the cell's surface for absorption. A
Cell membrane Outer layer composed of lipids and proteins. Controls the permeability of the cell to water and dissolved substances. A, P
Cytoplasm Viscous fluid mixture that occupies most of the cell's interior. Wraps the nucleus and contains biomolecules, organelles and a protein fiber network (the cytoskeleton). Medium in which organelles and other internal structures exist in. The fiber network makes the cytoskeleton, which supports the shape of the cell and anchor organelles to fixed positions. A, P
Mitochondria
(mitochondrion)		 Elongated organelles enclosed in a double membrane, the inner one with folds called cristae. Sites of cellular respiration, which converts sugars and fats into energy through oxidation. A, P
Chloroplasts Elongated organelles enclosed in a double membrane and with vesicles containing chlorophyll. Sites of photosynthesis. P
Ribosomes Tiny organelles composed of proteins and RNA, not enclosed in a membrane. Some are free in the cytoplasm, some are attached to endoplasmic reticulum. They are the only organelles present in all cells, including prokaryotics. Sites of protein synthesis. A, P
Endoplasmic reticulum Extensive system of internal membranes. May be smooth or rough: the latter has ribosomes attached to its membrane. Site of synthesis, modification and transport of various organic biomolecules. A, P
Golgi apparatus Flattened stacks of membranes. Used in the collection, packaging, and distribution of synthesized molecules. A, P
Secretory vesicles Membrane enclosed sacks created at the Golgi apparatus. These structures contain cell secretions, like hormones and neurotransmitters. The secretory vesicles are transported to the cell surface where they release those substances outside the cell (exocytosis). A, P
Vacuoles Elongated organelles enclosed in a membrane. Few and large in plant cells. Used to store sap (water and sugars) or waste products. A, P
Lysosomes Spherical organelles enclosed in a membrane. Contain digestive enzymes for breaking down old cellular components or ingested food (smaller cells, big macromolecules). A
Centrosome A pair of hollow tubes (the centrioles) surrounded by protein fibers in a star-like arrangement. Plant cells have an equivalent structure. Move and organise chromosomes during mitosis and meiosis. A
Nucleus Double membrane structure that encases chromatine. Controls the cellular activity. A, P
Chromatine Long strands of DNA and protein. During cell division it is packaged into chromosomes. The DNA stores hereditary information in small units of information called genes, and expresses it. A, P
Nucleolus Highly condensed chromatine loops. Area were ribosomes are manufactured. A, P
Topic 1.  Tissues

In multicellular beings there may be different types of cells, each type being specialized in an specific function, and having the specific shape that allows them to fulfill that function the best. Each of those types is called a cellular tissue; examples are the vascular tissue (plants) or the blood tissue (animals). One tissue may have several subtypes of cells (e.g. white blood cells and red blood cells). The human body contains over 200 different types of cells.

The four main types of human tissues are the following:

Epithelial tissue Composed of layers of cells that line organ surfaces such as the surface of the skin or the inner lining of the digestive tract. Serves for protection of organs (as in the skin), secretion of substances (when it forms glands - in the skin, in the digestive tract, etc.), and absorption of substances (as in the intestine).
Muscle tissue Composed of very long cells (up to several cm) called muscle fibres. They have more than one nucleus, are able to expand and contract (thanks to a dense protein network that takes up most of the cellular space), and so, are specialized in movements. There are three kinds: cardiac muscle (found in the heart), skeletal muscle (attached to bones and under voluntary control) and smooth muscle (not in the heart or attached to bones and under involuntary control, as in the wall of the stomach).
Nerve tissue Composed of cells with many projections that are specialized in contacting other cells and transmitting messages via electrical signals.
Connective tissues Usually specialized in holding together different organs or tissues. It is composed of cells usually very separated by an abundant extracellular matrix. The main types are the bone tissue (in bones, with matrix rich in apatite, a mineral rich in P and Ca), the cartilage tissue (in cartilages), the adipose tissue (as in the fatty layer under the skin - the hypodermis), the fibrous connective tissue (in ligaments and tendons), the loose connective tissue (as in the skin's dermis) and the blood.
Topic 1.  Organs, Systems and Apparatuses

There are some tasks in a multicellular being that must be achieved by cells of different kinds working together (such as pumping blood throughout the human body). In this case, cells of different tissues gather and make up an organ (epithelial, connective, muscle and adipose cells make up the heart).

Several organs working together in a common general task make up an organ system, e.g., the heart and the blood vessels make up the circulatory system. And when two organ systems work cosely together in a common function are said to constitute an apparatus: the muscular system and the skeleton form the motor apparatus, because both contribute to the function of locomotion in an animal.

Put simple, the human organ systems contribute to the three vital functions as follows:

  • Nutrition is fulfilled through:
    • The Digestive System, which (a) takes in the food, (b) breaks it down into nutrients and other substances, (c) absorbs the nutrients into the blood, and (d) gets rid of the non assimilable substances in the form of faeces.
    • The Circulatory System (a) transports those absorbed nutrients to all the cells of the body and (b) transports waste substances to the kidneys, the sweat-glands and the lungs.
    • The Excretory System expells of the waste substances arriving to the kidneys, by producing and releasing urine.
    • The Respiratory System (a) takes in oxygen (a nutrient) which is absorbed into the blood and (b) gets rid of the carbon dioxide (a waste substance).
  • Reproduction is carried out through the male and female reproductive systems which (a) produce the specialized reproductive cells (sperm and egg cells), (b) allow those reproductive cells to join in pairs, and (c) grow the embryo coming out of a fertilised egg-cell.
  • Interaction is fulfilled through:
    • The Sensory Organs, which continuously detect bits of information coming from the inside of the body or from the environment.
    • The Nervous System, which collects that sensitive information, interprets it, and generates response orders.
    • The Endocrine System, which cooperates in conveying those response orders by means of substances, called hormones, that are released by glands and travel through the blood.
    • The Skeleton and the Muscle System, which carry out most of those response orders produced in the nervous system.
Topic 2.  Vocabulary: Nutrition
Nutrition Getting the matter and the energy that every living being needs to grow, survive and reproduce. As it also involves the removal of waste substances and residual energy, it can be described as an exchange of matter and energy with the environment.
Breathing The movements performed by the lungs (along with the rib cage) to inhale and exhale the atmospheric air.
Respiration The process carried by the mitochondria, whereby small energetic nutrients (monosaccharides, fatty acids) are burnt with the help of the oxygen to produce the energy that the cells need. This process also involves the removal of CO2, H2O(g), and heat.
Gas exchange You need to convey O2 from the atmospheric air to the mitochondria and to convey the CO2 produced in the mitochondria to the atmospheric air. To do this, two gas exchanges are needed: (a) between the alveoli and the blood and (b) between the blood and the cells of every organ in your body. The blood vessels that take part in both gas exchanges are always the capillaries, because of their very thin membranes.
Blood The fluid that, amongst other things, conveys (a) the oxygen from the lungs to the cells, (b) the other nutrients from the small intestine to the cells, (c) the CO2 from the cells to the lungs, and (d) the other waste substances from the cells to the kidneys and the sweat glands.
Heart The organ that pumps the blood throughout all the body. It has two chambers to receive the blood (right and left atria) and two others to expell the blood (the left and right ventricles). Two valves (tricuspid and mitral) control the passing of the blood from the atria to the ventricles, and two other valves (aortic and pulmonary) control the passing of the blood from the ventricles to the arteries.
Blood vessels The organs that transport the blood throughout all the body. The arteries transport the blood from the heart to the organs (small arteries are called arterioles), the veins from the organs to the heart (small veins are called venules), and the capillaries are the very thin ones that perform the exchange of gases between the blood and the cells or the blood and the alveoli.
Excretion Disposing of the waste substances produced by the cells. It is done through the exhalation movement of the lungs, the kidneys and the sweat glands.
Topic 2.  Vocabulary: Digestive System
Peristalsis The wavelike muscular contractions of the digestive tract by which its contents are forced to move onwards. It is performed by the ring-like muscles of the walls of the esophagus, the stomach and the intestines.
Bolus The food mass that crosses the esophagus after having undergone a first digestive stage in the mouth.
Chyme The fluid food mass that is produced in the stomach when the bolus undergoes a second digestive stage.
Chyle The very fluid food mass that is produced in the duodenum when the chyme undergoes the third digestive stage.
Enzymes They are special proteins that behave as catalysts, i.e., they accelerate each and every chemical reaction in your body; otherwise, those chemical reactions wouldn't take place, or would do at a very slow pace. Enzymes are very specific and each one can catalise only one chemical reaction: for instance, the only thing that salivary amylase can do is breaking the starch into maltose.
Digestive enzymes The enzymes that break down the long molecules in the foods into much smaller ones that can later on be absorbed into the bloodstream. The main ones are the amylases (break down carbohydrates into sugars), the proteases (break down proteins into aminoacids) and the lipases (break down the lipids into glycerol and fatty acids). They come in the following digestive juices: the saliva, the gastric juice, the pancreatic juice and the intestinal juice.
Bile One of the five digestive juices. It is produced by the liver, stored in the gall-bladder, and it is greenish. It is necessary mostly not to carry digestive enzymes to the duodenum, but to transport bile salts to the duodenum. The bile salts are necessary to help the lipids to "dissolve" in the chyle, forming small droplets, easy to be attacked by the lipases. This process is called emulsification.
Villi The finger-like folds in the small intestine. They increase greatly the absorption surface in the small intestine (otherwise, the absorption of the nutrients from every meal would last for weeks). To allow an easy passing of the nutrients, they are very thin. Inside them, the nutrients are collected by capillary vessels and lymphatic vessels, and end up in the bloodstream.
pH A measurement that expresses the level of acidity of a substance: the lower the pH, the greater the acidity; the higher the pH, the greater the alkalinity. Substances with a pH of 7 are neutral, i. e., neither acid nor alkaline.
Lymph A clear fluid that circulates through the vessels of the lymphatic system. It collects the lipids in the small intestine and transports them to the bloodstream near the neck; it also helps the maturing of the young white blood cells before they are sent to the blood.
Topic 2.  Functions of the Digestive System
What Where
Digestion Breaking down the foods into small molecules that the blood can absorb later on (the nutrients) and into somewhat bigger molecules that can't be absorbed (dietetic fibre and others). Mouth, stomach and duodenum
Absorption The small nutrients from the digested foods pass from the digestive tract to the blood and the lymph. Jejunum and ileum
Elimination The indigestible molecules of the foods and some other waste substances are expelled out of the body. Rectum and anus
Topic 2.  Digestive Juices
Produced by Released to
Saliva Salivary glands (parotids, sublinguals and submandibulars). Mouth
Gastric juice Small glands in the lining of the stomach. Stomach
Bile Liver (and stored in the gall-bladder). Duodenum
Pancreatic juice Pancreas. Duodenum
Intestinal juice Small glands in the lining of the duodenum. Duodenum
Mind Map: Food additives
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Topic 3.  Vocabulary
CoordinationOne of the main three vital functions. It refers the ability of one living being to be aware of the events happening inside or outside itself and react to them accordingly. It requires (a) the detection of the stimuli by some receptor, such as the sensory organs, (b) the transmission of that sensory information to some control centre, (c) interpreting that sensory information and generating the response by the mentioned control centre, (d) transmitting the motor information that refers the response, and (e) performing the response by some effector, which, in the human body, is a muscle or a gland.
In the human body, the aforementioned stages are performed by the following structures:
 (a) by sensory organs or disperse sensory cells;
 (b) by the afferent nerves;
 (c) by the Central Nervous System;
 (d) by the efferent nerves, the endocrine glands and the hormones;
 (e) by the muscles and the glands.
NeuroneOr neuron (Am), or nerve cell. It is the main type of cells in the nervous system. They work in groups and communicate between each other by transmitting nerve impulses. There are three types: (a) sensory neurones, which transmit sensory information from the receptors to the CNS, (b) motor neurones, which transmit the motor information from the CNS to the effectors, and (c) relay neurones, that occur in the CNS, and are the ones that decide the responses once they have interpreted the sensory information generated by a stimulus.
Nervous circuitIt is a circuit formed by a sequence of neurones that connect a receptor with an effector, in order to trigger an appropriate response to the stimulus that has been detected. It consists of, at least, one sensory neurone, one relay neurone, and one motor neurone.
GanglionIt is a cluster of somas and dendrites of a group of neurones. They belong to the PNS, and often interconnect with other ganglia to form a more complex cluster known as a plexus.
NerveBundles of bundles of axons of many neurones packed together. They belong to the PNS and (a) convey sensory information from the receptors to the CNS (afferent nerves), or (b) motor information from the CNS to the neurones (efferent nerves), or (c) both (mixed nerves).
HormoneChemicals secreted by the endocrine glands into the bloodstream, that act as chemical messengers, this is, they trigger certain responses in the target cells that are meant to react to some variation of the external medium (as when a secretion of adrenaline helps you to face succesfully some sort of threat) or some variation of the internal medium (as when a secretion of insulin helps you to keep an adequate level of sugar in your blood).
Target cellThe target cells (which belong to the so called target organs) are called like that because they are the specific target of an specific hormone. This means that, although the hormones are released into the bloodstrem, and therefore reach every cell in the organism, only a group of cells are going to react to the arrival of any particular hormone: these are the target cells, and what makes them be such, is the possession in the surface of their membranes of molecules that act as specific receptors to one specific hormone. It is the coupling of a hormone to those receptors what triggers the final response accomplished by the target cells (opening up your pupils, lowering the levels of glucose, etc.).
Topic 3.  Structural Organisation of the Nervous System
Central Nervous System
  • Brain (= encephalon). Enclosed by the skull and the meninges. Main organs: cerebrum, cerebellum and brain stem.
  • Spinal cord. Enclosed by the backbone (= spinal column, = spine) and the meninges.
Peripheral Nervous System
  • Nerves: bundles of neurones' axons. Functional types: afferent, efferent or mixed. Structural types: cranial (12 pairs) or spinal (31 pairs).
  • Ganglia: clusters of neurones' somas.
Topic 3.  Facts About Neurones
  • They occur only in the Nervous System, but they are not the unique type of cells in it: there are, also, the glial cells, which assist the neurones in several tasks (nutrition, disposal of wastes, defense, regeneration…).
  • They have two parts: the cell body or soma, and the nerve fibers: these are prolongations of the soma that can be two kinds: the axon (single, long, branched only at the end) and the dendrites (usually many, short and highly branched). The dendrites may be lacking.
  • Their function is transmitting an electric current called nerve impulse along circuits that connect the sensory information collected by the receptors with the responses performed by the effectors.
  • The nerve impulse is transmitted always in the same direction: from the dendrites (if any) to the soma, and from the soma to the axon. The axon terminals will make connections with other neurones or, at the end of the circuit, with an effector.
  • Many axons (the ones of the PNS and the ones that make up the white matter of the CNS) are wrapped by Schwann cells, that make up the myelin sheath, which helps speeding up the transmission of the nerve impulse.
  • The demyelination of myelinated axons is characteristic of some serious diseases such as multiple sclerosis.
  • The regeneration of damaged neurones in the CNS is not possible, but the myeline layer helps regenerate the damaged axons of the PNS (only).
  • Two consecutive neurones in a nervous circuit do not touch each other, and so, the nerve impulse has two "jump" over that gap (the synapse); this is acomplished by means of certain molecules called neurotransmitters (e.g. dopamine, endorphin).
  • The low production of certain neurotransmitters (or the inhability to use them) is the hallmark of several diseases such as the Parkinson's disease.
Topic 3.  Endocrine Control

In many cases, when an endocrine gland releases a hormone, it is upon request of some controlling organ, which, at the end of the hierarchical chain, is always the brain. But who tells the brain to tell the hypothalamus (the so called master gland), to tell the hypophisis to tell the breasts (via the secretion of oxytocin) to secrete milk? The sensory cells (receptors) that detect the baby's suckling do. They send nerve impulses to the brain informing of this event, and then the brain starts the chain of orders.

There are also cases in which it is the same gland that produces the hormone the one that detects the stimulus that will finally lead to the secretion of the hormone. It is the pancreas itself the organ that learns about the rise of the level of sugar in blood, and responds to it by secreting insulin. And if the pancreas notices a low level of glucose in blood, it, without asking anyone, will release glucagon, which will help to take more glucose into the blood. Insulin and glucagon are antagonist hormones, because they do opposite things. The have in common who secretes them (the pancreas) and their target organs (chiefly the liver and the muscles).

As more glucose in blood leads to less glucose in blood (through the action of the insulin) and less glucose in blood leads to more glucose in blood (via glucagon), these two are examples of negative feedback in endocrine control. But secreting milk when the baby suckles leads to keep on secreting more milk: the stimulus empowers itself, and this is called positive feedback.

Topic 4.  Vocabulary: Male Reproductive System
[Adapted from Faqs.org]
ScrotumExternal sac enclosing the testes.
TestesMale gonads that produce sperm cells, a 2-5% of the seminal fluid, and secrete testosterone.
Seminiferous tubulesTightly coiled tubes within the testes that produce sperm.
EpididymisPortion of the testes in which sperm mature or fully develop.
Vas deferensAlso ductus deferens. Passageway that carries sperm from the epididymis to the ejaculatory duct.
Seminal vesiclesGlands located at the base of the bladder that produce around a 70% of the seminal fluid.
Ejaculatory ductDuct formed by the union of the ductus deferens and the duct of the seminal vesicle, that carries the semen up to the urethra.
ProstateMuscular gland in males that surrounds the first inch of the urethra. It produces almost a 30% of the seminal fluid.
Bulbourethral glandsAlso Cowper's glands. Glands located at the base of the penis, that at the beginning of sexual arousal secrete a fluid which helps to lubricate the urethra for spermatozoa to pass through, and to help flush out any residual urine. This fluid can carry sperms from previous ejaculations.
PenisMale organ of reproduction and urination.
PrepuceAlso foreskin. The fold of skin over the glans or tip of the penis.
CircumcisionSurgical removal of the prepuce of the penis.
ErectionStiffening, lengthening and rising of the penis, which occurs during sexual arousal, though it can also happen in non-sexual situations. It is primarily due to the dilation of the arteries that supply blood to the penis (which allows more blood to fill the three spongy chambers in the penis) and the constriction of the veins that carry blood away from the penis. This way, more blood enters than leaves the penis until an equilibrium is reached and a constant size is achieved.
EjaculationSudden ejection of semen from the penis.
SemenThick, whitish, somewhat sticky fluid composed of sperms and seminal fluid that is propelled out of a male's reproductive tract during ejaculation. Normal human ejaculated semen, as defined by the WHO, has a volume of 2 ml or greater, pH of 7.2 to 8.0 (slightly alkaline), sperm concentration of 20 million spermatozoa per ml or more, and a motility of 50% of the spermatozoa, with at least a 25% being able to move forward.
Topic 4.  Vocabulary: Female Reproductive System
[Adapted from Faqs.org]
OvariesFemale gonads in which ova are produced and that secrete estrogens and progesterone.
Ovarian folliclesStructures within an ovary consisting of a developing egg surrounded by follicle cells.
Corpus luteumYellowish remains of a burst ovarian follicle that secretes progesterone.
OvulationRelease of a mature ovum from an ovary.
FimbriaeFingerlike projections at the end of a fallopian tube that partially surround an ovary.
Fallopian tubesAlso ovarian tubes. Tubes connecting an ovary to the uterus and through which an ovum is transported. They are the place of fertilization.
UterusAlso womb. The hollow organ in females that receives, retains, and nourishes a fertilized ovum or egg.
MyometriumMiddle layer of the uterus composed of interwoven muscle cells.
EndometriumInner layer of the uterus that provides nourishment for a developing embryo and fetus and that sloughs off during the regular menstrual cycle.
CervixLower necklike portion of the uterus leading into the vagina.
VaginaMuscular tube in women that extends from the cervix of the uterus to the vaginal opening.
VulvaFemale external genital organs, composed of the mons pubis, the labia majora, the labia minora, the clitoris, the urethral opening, the vaginal opening and the greater vestibular glands.
Mons pubisFatty, rounded, hairy area at the top of the vulva.
Labia majoraOuter, hairy skin folds of the vagina.
Labia minoraInner skin folds of the vagina.
ClitorisSmall protruding mass of erectile tissue at the top of the labia minora.
Greater vestibular glandsPair of mucus-secreting glands that lubricate the lower portion of the vagina.
HymenThin membrane partially covering the external opening of the vagina.
Topic 4.  Vocabulary: Menstrual Cycle
[Adapted from Faqs.org]
MenarcheBeginning of menstruation or the first menstrual period.
MenopausePeriod in a woman's life when menstrual activity ceases.
MenstruationAlso menses. Periodic (monthly) discharge of blood, secretions, tissue, and mucus from the endometrium in the absence of pregnancy.
Topic 4.  Vocabulary: Gametes
[Adapted from Faqs.org]
GonadsSex organs in which reproductive cells develop.
GametesReproductive or sex cells. They are different to any other cell in the body in which they only have half of the chromosomes than a normal somatic cell.
OvaFemale gametes or eggs (singular: ovum).
ZygoteFertilized ovum. By successive mitosis, it will convert into an embryo, then a fetus, and finally a newborn.
SpermAlso spermatozoon. Mature male sex or reproductive cell. They need to be produced at a slightly lower temperature than the usual in the inside of the human body.
AcrosomeTip of the head of a sperm cell that contains enzymes to digest the membrane of an ovum.
Topic 4.  Vocabulary: Pregnancy, Childbird and Nursing
[Adapted from Faqs.org]
ChorionThe outermost membrane that surrounds the embryo/fetus during pregnancy. It is in contact with the amnion and generates the placenta.
AmnionFluid-filled sac that surrounds a developing embryo/fetus. It provides room and cushioning to the embryo/fetus.
PlacentaTemporary organ developed after the implantation of an embryo, when the chorionic villi invade the endometrium. It provides nutrients to a developing fetus, carries away wastes, and produces hormones such as estrogens and progesterone.
Umbilical cordStructure that connects the embryo/fetus to the placenta.
Alveolar glandsGlands within the mammary glands that produce milk.
Lactiferous ductsDucts that carry milk from the alveolar glands to the surface of the nipple of a breast.
AreolaCircular, darkened area surrounding the nipple of each breast.
Topic 4.  Vocabulary: Hormonal Control of the Reproduction
[Adapted from Faqs.org]
Luteinizing hormoneHormone secreted by the anterior pituitary that stimulates, in women, ovulation and the release of estrogens and progesterone by the ovaries and, in men, the secretion of testosterone by the testes.
Follicle-stimulating hormoneHormone produced by the anterior pituitary gland that stimulates the development of follicles in the ovaries of females and sperm in the testes of males.
TestosteroneMale hormone secreted by the testes that stimulates the growth of the male reproductive organs and brings about the secondary sex characteristics.
EstrogensFemale hormones secreted by the ovaries that bring about the secondary sex characteristics and regulate the female reproductive cycle.
ProgesteroneFemale hormone secreted by the ovaries that makes the uterus more ready to receive a fertilized ovum and regulate the female reproductive cycle.
ProlactinHormone secreted by the anterior pituitary that stimulates the mammary glands to produce milk during nursing.
OxytocinHormone produced by the hypothalamus and stored in the posterior pituitary that stimulates contraction of the uterus during childbirth and secretion of milk during nursing.
Presentation: Smoke, the convenient truth
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Topic 6.  Physical Properties of the Minerals
ColourThe colour of a mineral is one of its most obvious attributes and the easiest physical property to determine. Unfortunately, as it results from a mineral's chemical composition and structure, the impurities and structural flaws that may be present can alter completely the colour with regards to the pure mineral. Hence minerals like fluorite and quartz may display a really wide range of colours. This makes colour not the most useful property in helping to characterize a particular mineral.
StreakThe streak refers to the colour of a mineral's powder, which is almost always the same, regardless the impurities and structural flaws of the mineral. Thus, it is much more reliable to characterize a mineral than the colour of the mineral itself. The streak is usually obtained by rubbing the mineral across a plate of unglazed porcelain. The streak and the mineral's typical colour may or may not be the same. Some examples of streaks of common minerals are pyrite (black), magnetite (black), halite (white).
Transparency /
Diaphaneity		A transparent mineral (diamond) allows all light to cross through; a translucent mineral (quartz) allows part of the light to cross through; an opaque mineral (pyrite) does not allow the light to pass at all.
LustreIt refers to the way in wich a mineral's surface reflects light. To some extent it is related to the transparency of a mineral; for instance, metallic minerals are always opaque and vitreous minerals are always translucent.
CleavageIn some minerals, bonds between layers of atoms aligned in certain directions are weaker than bonds between different layers. In these cases, breakage occurs along flat surfaces parallel to those zones of weakness. In some minerals, a single direction of weakness exists, but as many as six may be present. Halite, which forms cubic crystals, presents 3 perfect cleavage directions.
HardnessIt depends on the strength of the chemical bonds and is measured by the ease or difficulty with which a mineral can be scratched. Diamond is the hardest mineral, because it can scratch all others. Talc is one of the softest; nearly every other mineral can scratch it. We measure a mineral's hardness by comparing it to the hardnesses of a standardized set of minerals first established by Friederich Mohs.
TenacityIt is a mineral's physical reaction to stress such as crushing, bending, breaking, or tearing. For example, according to its tenacity, a mineral can be brittle (easy to powder with a hammer), sectil (easy to cut with a knife), malleable (easy to flatten with a hammer, as metallic minerals) or ductile (easy to stretch into a wire, as metallic minerals).
Growth habitRefers to the shape a mineral develops when it is not constricted by lack of available space. For example, quartz forms six-sided prisms capped with pyramid-like faces; halite occur as cubes; and pyrite develop cubes or pentadodecahedrons (polyhedrons with 12 pentagonal faces).
Specific gravityIt's a comparison of the density of a mineral to that of water. For example, quartz has a specific gravity of 2.6 because it is 2.6 greater than that of water. You can also say that it has a density of 2.6 g/cm3
MagnetismWhen a mineral can be attracted by a magnet or act themselves as magnets. The best example is magnetite.
Electrical conductionWhether an electric current can easily pass through a mineral (such as in all metallic minerals and graphite) or not.
FeelWhat you perceive when you touch a mineral. It can be rough, smooth, greasy (talc), cold (diamond)…
TasteWhat you perceive when you lick a mineral. Halite, for instance, tastes salty.
Topic 6.  Main Types of Mineral Lustre
[Available in Google Docs]
LustreOpacityExamples
AdamantineTransparentDiamond
VitreousTranslucentQuartz, Halite, Olivine
WetTranslucentFluorite
ResinousTranslucentYellow and red sphalerite varieties
WaxyTranslucentTalc
GreasyTranslucentMilky quartz
SilkyTranslucentFibrous gypsum
PearlyPoorly translucentMica aggregates
Dull metallicOpaqueGraphite
MetallicOpaquePyrite, Galena, Magnetite
EarthyOpaqueKaolinite
Topic 6.  Properties of Some Common Minerals
[Available in Google Docs]
CompositionColourStreakTransparencyLustreHardnessGrowth habit
GraphiteCDark greyBlackOpaqueDull metallic1.7Foliated, massive
PyriteFeS2Pale goldenBlackOpaqueMetallic6.5Cubes, pentadodecahedrons
CinnabarHgSVermilion redBright redOpaqueAdamantine / Dull metallic (aggr.)2.2Massive
GalenaPbSGreyGreyish blackOpaqueMetallic2.5Cubes, octahedrons
MagnetiteFe3O4BlackBlackOpaqueMetallic5.7Octahedrons, massive
HematiteFe2O3Reddish greyRedOpaqueMetallic6Tabular
HaliteNaClColourlessWhiteTranslucentVitreous2.5Cubes, etc.
FluoriteCaF2Colourless, yellow, green, blue…WhiteTranslucentWet vitreous4Cubes, etc.
CalciteCaCO3Colourless, white…WhiteTranslucentVitreous3Rhombohedrons
AragoniteCaCO3Reddish greyWhiteTranslucentVitreous4Hexagonal twinning, etc.
GypsumCaSO4·2H2OWhite, grey, redWhiteTranslucentSilky vitreous2Lamellar, fibrous
QuartzSiO2Colourless, white, grey, yellow, violet…WhiteTranslucentVitreous76-sided prisms
OrthoclaseSilicatePinkishWhiteTranslucentVitreous6Massive
Biotite / Black micaSilicateColourless / Black (aggr.)GreyTranslucentVitreous / Pearly (aggr.)2.7Lamellar
Muscovite / White micaSilicateColourless / White (aggr.)WhiteTranslucentVitreous / Pearly (aggr.)2.2Lamellar
OlivineSilicateOlive greenWhiteTranslucentVitreous6.7Granular
TalcSilicatePale green, grey, whiteWhiteTranslucentWaxy vitreous1Massive
Topic 7.  Rock Grains

Sedimentary rocks can be made up of clasts or detritus (rock grains) weathered from other rocks by river waters, wind, coastal sea waters, glaciers, living beings, etc. This kind of sedimentary rocks are called detrital rocks.

They're classified upon the grains that they are made up of. First up, grains may be all the same size, uniform, as in a sandstone, or different sizes, as in a conglomerate. Secondly, grains may be bigger or smaller. The following table shows roughly how rock grains are classified upon their size:

Diameter
Clay< 0.004 mm
Silt< 0.06 mm
Sand< 2 mm
Gravel< 6 cm
Cobble< 25 cm
Boulders> 25 cm

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