Biology

• A carbon footprint is the amount of CO2 released into the atmosphere as a result of the activities of an individual, organization or community.
• Natural populations are subject to environmental checks which limit their size and keep them from growing larger than a certain point.
• Environmental checks are called environmental checks and they limit the size of natural populations, which tend to level off and remain stable from year to year.
• Oil spills and hot water can block out oxygen and light, causing coral bleaching.
• Greenhouse Gases, including CO2, CH4, water vapour, Nitrogen oxide, are essential to keep the earth from being too cold, but their emissions due to human activities have resulted in climate change.
• Climate Change is a global phenomenon, in which the earth’s temperature continues to rise and this rise is largely linked to a rise in CO2 levels as a result of man’s activities, leading to consequences such as melting ice caps, rising sea levels, and changing weather patterns.
• A Greenhouse is an artificially controlled environment, providing optimum conditions for plant growth, regardless of external conditions.
• Global Solutions to climate change include Conservation, which involves managing the earth’s resources so as to restore and maintain a balance between the needs of humans and the needs of other species.
• Conservation at an individual level includes using recycled products, disposing of waste properly, not removing plants and animals especially eggs from their natural environment, and being conscious of energy use.
• Land Pollution is caused by pollutants such as insecticides and herbicides, non-biodegradable waste, and can increase bacteria, attract pests, and cause diseases.
• Humans have two separate systems to detect and respond to stimuli: the nervous system, which detects and responds to external stimuli, by means of nerve impulses which travel along special pathways called nerves, and the endocrine system, which detects and responds to internal stimuli by means of chemical messengers, called hormones, which are secreted into blood and transported by blood.
• Products used to lighten skin include acids derived from natural products as well as chemicals, such as hydroquinone.
• The nervous system is divided into two main parts: the Central nervous System, made up of the brain and spinal cord, which runs down the centre of the body, and the Peripheral Nervous System, made up of the cranial nerves, which branch off the brain, and the spinal nerves, which branch off the spinal cord.
• The brain has three main areas: the Cerebrum, responsible for conscious thought, motor and sensory coordination, the Cerebellum, responsible for balance and accurate and precise movement, and the Medulla oblongata, responsible for automatic functions and continues into the spinal cord, which keeps you alive if you are “brain dead”.
• The entire Nervous System is made up of highly specialized cells called neurones, which have a cell body with nucleus, cytoplasm and organelles, dendrites, which are extensions of the cell body that collect messages, an axon, a long extension of cytoplasm that transmits impulses, axon terminals, which connect to other neurons or effectors, a myelin sheath to insulate the axon and speed up impulses, and gaps in the Myelin Sheath called Nodes of Ranvier.
• Actions brought about as a result of a stimulus can be voluntary, controlled by the cerebrum resulting in a conscious act requiring thinking, which may be fast or could take a long time, or involuntary/reflex, which do not involve thinking and are very fast.
• There are two types of reflexes: Cranial Reflex, which takes place in the region of the head e.g blinking, sneezing, pupil response, and Spinal Reflex, which take place below the head and involve the spinal cord only e.g the knee jerk reflex, dropping a hot object, jumping when startled.
• Sweating is a process where sweat glands surrounded by blood capillaries extract water along with mineral salts and a small amount of urea, and pass these up the sweat ducts, to come out of the sweat pores and lie on the skin.
• Cataract is a cloudiness of the lens or cornea of the eye, usually develops in older people.
• Hair erector muscles relax, causing hairs to lie flat on the skin.
• The dermis is the living part of the skin which has several nerve endings, which are able to detect various stimuli such as touch, pressure, temperature and pain.
• Vasoconstriction is a process where hair erector muscles contract, pulling on hairs, causing them to stand upright, trapping warm air against the skin.
• Subcutaneous fat is a fatty layer in the skin that helps to insulate from the cold, especially important in aquatic mammals and those who live in very cold conditions.
• Vasodilation is a process where arterioles close to the surface dilate (widen) and the ones below will constrict, so more blood is brought close to the surface, and heat is lost at a faster rate.
• A Conditioned Reflex is an action brought about automatically without thinking, but is as a result of learning, e.g Pavlov’s dog, which learned to salivate at the sound of a bell because he associated it with the presence of food.
• The upper layer of the epidermis is made of a layer of dead cells containing keratin, which provides mechanical protection.
• Skin lightening (Bleaching) is a process where the colour of our skin is changed due to how much melanin it produces and is determined by our genes, which we inherit from our parents.
• Astigmatism is an unevenness in the shape of the cornea.
• Skin care is necessary as the skin has its own natural oils and a protective layer to prevent from drying out, as well as melanin to offer protection from damaging ultra violet rays of the sun.
• The skin is largely responsible for maintaining a constant body temperature (homeostasis).
• The skin also has a small excretory function as small amounts of metabolic wastes are lost with sweat.
• The layer below the upper layer of the epidermis has the pigment, melanin, which protects against skin damage.
• The skin is considered to be the largest organ in the body, forms a protective layer, acts as a sense organ, is important in temperature regulation, plays a small role in excretion, and provides protection.
• Glaucoma is the leading cause of blindness in the Caribbean and is caused by a build-up of aqueous humour in front of the eye which builds up excess pressure, affecting the optic nerve.
• Human conditioned reflexes include typing, walking, riding a bicycle.
• A Reflex Arc is the pathway taken by nerve impulses in a reflex action.
• Accommodation is the ability of the eye to focus on an object close to the eye or far away.
• As conduction of nerve impulses is like electrical conduction, impulses cannot cross the gap.
• Changes in the Eye during Accommodation: Distant Viewing, Near viewing, Ciliary muscles relax, contract, Suspensory ligaments tighten, loosen, lens becomes thin, becomes thick.
• The retina is the layer which is the real receptor of the eye, has sensitive cells which receive light: Cones – respond to bright light and are responsible for seeing colour and they are mostly found around the fovea, Rods – respond to dim light and detect the brightness of light rather than actual colour.