P Flashcards
Palisade mesophyll
Tissue in leaves that contain many chloroplasts and are the main site of photosynthesis.
Pancreas
The organ in the abdomen that produces digestive enzymes and makes insulin and glucagon that regulate the concentration of glucose in the blood.
Partially permeable membrane
A membrane that allows small molecules to pass through, but does not allow large molecules to pass through.
Passive immunity
Providing antibodies from another person or an animal; the person receiving the antibodies does not make the antibodies himself or herself.
Pathogen
an organism that causes a disease.
Pectinase
An enzyme that breaks down cell walls of plants.
Peripheral nervous system
Nerves that arise from the brain and spinal cord and go to all the organs of the body.
Peristalsis
A wave of muscular contraction that squeezes food down the oesophagus to the stomach.
Pesticide
A Chemical that kills pests.
Phagocyte
A type of white blood cell that ingests and destroys pathogen.
Phagocytosis
A type of white blood cell that ingests and destroys pathogens.
Phenotype
The physical or other features of an organisms due to both its genotype and enviroment.
Phloem
The plant tissue that transports sugars and amino acids.
Photosynthesis
Process by which plants manufacture carbohydrates from raw materials using energy from light.
Phototropism
A growth response of a plant to the direction of light.
Pituitary gland
A gland at the base of the brain that secrets hormones to controls the activity of other organs, e.g. kidneys, testes and ovaries.
Placenta
The organ that connects a mammalian embryo to its mother and through which it receives food and oxygen and removes carbon dioxide and chemical waste.
Plague
(1) a mixture of food remains, saliva and bacteria which can build up on the surface of teeth; (2) fatty deposit in the lining of an artery.
Plasma
The liquid part of the blood which transports dissolved foods, urea, carbon dioxide and hormones.
Plasmid
The liquid part of the blood which transports dissolved foods, urea, carbon dioxide and hormones.
Plasmolysis
The separation of the cell membrane from the cell wall of a plant cell when water leaves the cell by osmosis.
Platelets
Small pieces of cells that release substances that cause blood to clot.
Pollination
The transfer of pollen from the anther of a flower to the stigma.
Pollution
The release by humans of materials or energy that will harm the enviroment.
Population
a group of individuals of the same species living in the same habitat at the same time.
Population growth
Growth in numbers of a population. In absence of limiting factors growth is usually exponential.
Predators
Animals that hunt and kill other animals for their food.
Prey
Animals that are hunted and killed for food by predators.
Producers
An organisms that makes its own organic nutrients usually using energy from sunlight through photosynthesis.
Progesterone
A hormone secreted by the ovaries and by the placenta that maintains the lining of the uterus during the second half of the menstrual cycle and during pregnancy.
Protease
An enzyme that breaks down proteins to amino acids.
Protein-energy malnutrition
Form of malnutrition in which energy and protein are limited in the diet, e.g. marasmus and kwashiokir
Proteins
Compounds made up of amino acids, which are needed for growth and repair of tissues in the body. They contain the elements carbon, hydrogen, oxygen, nitrogen and sulfur.
Puberty
The age at which secondary sexual characteristics appear in boys and girls.
Pulse
When the left ventricle of the heart contracts, it forces blood out of the heart along the arteries. The arteries swell and this can be felt as a pulse in various parts of the body, such as the wrist.
Pupil
The hole through which light enters the eye. The size of the pupil is controlled by the iris.
Pyramid of biomass
A way to show biomass at each tropic level in an ecosystem. the area of each horizontal bar is proportional to each mass of living material at each tropic level.
Pyramid of numbers
A way to show numbers of organisms at each trophic level in an ecosystem. The area of each horizontal bar is proportional to the number of individuals at each tropic level.
