Glossary of Biological Terms

Biology Dictionary ©

Aquatic respiration
A hypothesis accounting for sap flow through the phloem system. Binocular Vision When the two eyes face forwards their field of vision overlaps allowing the animal to judge depth. This is important because most birds have neopulmonic parabronchi as well as paleopulmonic parabronchi and, although air flow through paleopulmonic parabronchi is unidirectional, air flow through neopulmonic parabronchi is bidirectional. Relative thickness of the arrows indicates the proportion of air streaming through the different areas of the respiratory system during the respiratory cycle. An active transport mechanism in cell membranes that consumes ATP to force hydrogen ions out of a cell and, in the process, generates a membrane potential. Valence and Covalent Bonding Concept 3: In birds, the thickness of the blood-gas barrier in the 7.

Reference Articles

Comparative Animal Respiration

The nostrils are then opened allowing air to rush into the mouth as pressure equalises. The air in the mouth is then forced into the lungs by further contraction of the oral cavity floor. Fish live in predominantly aquatic environments however there are exceptions, such as the lung fish which are able to utilise lungs to obtain oxygen. Aquatic fish however use a set of respiratory organs known as gills. Gills are highly vascularised with a large surface area, short diffusion distance and an always moist surface.

Their structure consists of:. In order to pass the oxygenated water over the gills fish have two main methods, either ram ventilate swim through the water with an open mouth forcing water to pass over the gills, stopping would cause the fish to drown or use a similar method to amphibians — a double force pump.

Both of these methods are unfortunately energy expensive. The mechanism of the double force pump method is as follows. The fish utilises the expansion and contraction of two cavities, the buccal cavity mouth and the opercular cavity gills:. The exposure of the gills to water poses certain problems concerning salt movement. In freshwater salt is able to easily diffuse out of the fish into the hypotonic water. To maintain a healthy salt concentration within their body, they:.

Marine fish on the other hand, have the completely opposite problem. Water is continuously lost from the fish and salt is continually being taken up. To maintain healthy levels of water and salt marine fish:.

Compared to other species, mammalian respiration is highly efficient; there is a very large surface area within the lungs which is maximised by the bubble like structure of the alveoli.

The lungs also benefit from very thin membranes between the moist layer within the alveoli and the blood. The blood supply to the lungs is very great. Mammals have a sealed thoracic cavity, which is sealed by the diaphragm. In conjunction with the ribs, the two sets of muscles are able to control breathing.

This process works in conjunction with the intercostal muscles connected to the rib cage. Contraction of these muscles lifts the rib cage, thus aiding in increasing the thoracic volume. Relaxation of the diaphragm compresses the lungs, effectively decreasing their volume while increasing the pressure inside them.

The intercostal muscles simultaneously relax, further decreasing the volume of the lungs. This increased pressure forces air out of the lungs. Conversely, contraction of the diaphragm increases the volume of the partially empty lungs, decreasing the pressure inside, which creates a partial vacuum.

Environmental air then follows its pressure gradient down to fill the lungs. The ventilation system of mammals is basically a suction pump. Just like mammals, birds have ribs, although they lack a diaphragm to seal the thoracic cavity. The thoracic and abdominal cavities are thus not separated and this single large body cavity is known as the coelom.

The lungs of the bird are connected to the wall of the coelom by connective tissue and are unable to enlarge themselves like mammalian lungs. Instead air is moved in and out of the bird by expanding the coelom; this enlarges air sacs connected to the coelom causing air to pass through the lungs and into the air sacs.

A complete avian respiratory cycle involves two inspirations and two expirations unlike mammals which involve only one. Endoparasite An animal that lives inside another animal's body, both eat the tissues and food. Endoskeleton An internal skeleton that supports an animal's body and is generally made of bone. Environment The term environment is used to describe the conditions surrounding a certain organism as a whole. This includes everything from the social structure of life contained within that environment from animals to plants, but also is a method of describing how all the different organisms in one area interact with each other.

The are numerous different environments throughout the world including desert environments, jungle environments and mountainous environments. The term environment basically refers to all living and non-living things in the world or a particular region.

Estimated Population Size How many of a particular species are thought to exist at this time. Evolution Evolution is the process by which different species of animals evolve, generally in accordance with natural selection and to make life more successful for the species.

For example, certain species of moth have known to completely change colour in just a few generations because of pollution, and the horse we know today evolved from having many toes, to just having a single toe today.

Exoskeleton An external skeleton that supports and protects the animal's body. External Fertilisation Fertilisation that occurs outside of the womb, normally in water. Family A level of classifying animals within an order. Orders are broken down in families and families are broken down further into smaller groups called genus.

Favourite Food The preferred food of an animal. For example, Penguins may eat Crab or Squid, but typically prefer to eat Fish - this may because they are easier to catch, eat or digest. Femur The femur is the thigh bone in all vertebrates that have four limbs including elephants, lions and humans.

Feral A feral animal is an animal that was brought up domestically but has then begun to live life in the wild. Fertilisation The meeting of a female animal's egg cell and a male animal's sperm, which creates a cell able of developing into a new animal.

Filter Feeder An animal that feeds by extracting small particles of food out of the water. Fish Fish are cold blooded vertebrates that live in the waters of rivers, lakes and oceans worldwide. Fish have scales covering their skin and usually an oily layer on the surface of the fishes skin, which helps to regulate the body of temperature of the fish.

Fish have gills on the sides of their heads which allows the fish to breath underwater, due to their complex respiratory breathing system. There thought to be around 32, different species of fish found in freshwater and saltwater sources alike, with over 1, of these now considered to be critically endangered. Fish are a stable food source for many species of mammals, birds and reptiles around the world.

Flight Feathers The wings and tail feather of a bird that are used in flight. Flipper A flat paddle-shaped limb that many aquatic mammals have. Fluke Many whales and their relatives have a rubbery tail flipper which is known as a fluke. Food Chain An animal food chain is the sequence of who eats whom within an ecosystem in order for each animal to obtain nutrition.

A food chain starts with the primary energy source, which is usually the sun and the food chain is then connected by a series of organisms that eat each other, in turn. The food chain starts with the sun and is then followed by the primary producers, then the primary consumer, then the secondary consumer, followed by the tertiary consumer and finishing with the quaternary consumer which is generally an animal that is eaten by nothing else and is therefore the end of the food chain.

Food chains are never the same as each ecosystem contains different organisms within it. If one part of the food chain is missing then there will be high population levels in the links before the missing part of the food chain, as nothing is eating them, and there will also be lower population levels in the links after the missing part in the food chain, as those animals have nothing to eat.

The food chain is then said to be out of balance, so it is crucial for food chains to remain unaltered in order for balance within the animal kingdom to remain. Primary Producer Primary producers are those organisms that require nothing but the natural resources of the Earth in order to thrive and survive.

Primary producers tend to be plants that are photosynthetic and these plants use the energy provided by sunlight in order to make their own food using a process called photosynthesis.

Other primary consumers include bacteria that make their own food using chemicals that are produced in natural vents in the ocean. Primary producers are also known as autotrophs and are vital to the survival of the animals that follow in the next stages of the food chain.

Primary Consumer The primary consumers are the next stage in the food chain behind the sun and the primary producers. The primary consumers are the herbivorous animals of the world and consume the primary producers autotrophs in order to gain their nutrition. For example, an insect primary consumer will eat the seeds and sprouts that are provided by grass primary producer.

Primary consumers are also known as heterotrophs. Secondary Consumer The secondary consumers link in with the food chain as they are the omnivorous animals that eat the primary consumers and the secondary consumers will occasionally eat the primary producers in order to supplement their diet. For example, a rat secondary consumer will eat an insect primary consumer that has gained its nutrition from eating the grass primary producer.

Secondary consumers are also known as heterotrophs. Tertiary Consumer The secondary consumers are followed by the tertiary consumers, the tertiary consumers tend to be the smaller carnivores of the animal kingdom.

The tertiary consumers only eat meat and therefore really on the consistency of the secondary consumer populations in order to continue to thrive as a species. For example, a snake tertiary consumer will eat a rat secondary consumer that has gained its nutrition from eating an insect primary consumer , and the insect has gained its nutrition from eating the grass primary producer.

Tertiary consumers are also known as heterotrophs. Quaternary Consumer The final part to the food chain are the quaternary consumers, and these are the animals that tend to be large carnivores and dominant predators within their natural environment. Quaternary consumers generally have few, if any, natural predators at all and this tends to be where the food chain ends.

For example, an eagle quaternary consumer will eat a snake tertiary consumer , that has eaten a rat secondary consumer , that has eaten an insect primary consumer , that has eaten the grass primary producer that has used the energy from the sun in order to make food.

Food Web The interlinking of a collection of food chains from one habitat. Genus A level of classifying animals within a family. Families are divided into sub-groups called genus which generally contain one or two animal species. Gestation Period The gestation period is the time from conception to birth in which a mammal embryo is developing.

The gestation period is different for almost every species of animal, for example, the gestation period for a human embryo is roughly 9 months but the gestation period for a kangaroo embryo is only around 30 days. Gill An external organ used by aquatic animals such as fish, to extract oxygen out of the water. Group Behaviour How an animal behaves when in a group. For example, Elephants live together in herds, whereas a Jaguar is a solitary animal which lives on its own.

Habitat The term habitat is used to describe a specific area where a particular animal lives, within an environment. Many animals have adapted to requiring specific conditions which can only be found in their natural habitat such as those animals that live in the polar regions that have longer, thicker body fur to keep them warm. Herbivore A herbivore is an animal that only eats plant material, algae and bacteria in order to gain its nutrition.

Those animals that are herbivorous have adapted to digest plant material specifically, such as elephants, donkeys and rabbits. Hermaphrodite An animal that has both male and female reproductive organs so that it is able to self-fertilize. Hibernation When an animal hibernates, it isn't as simple as the animal just sleeping for a long time.

When an animal sleeps, the animals brain is still active so the animal is able to move around in their sleep and can also wake up quickly. When an animal hibernates, the animals heart rate slows down, the animals body temperature drops as it is exposed to cold surroundings and the animals breathing slows down meaning that the animal takes longer than usual to wake up. The animal spends the months before it hibernates eating lots of food to make sure its body has enough energy to survive the winter.

Some animals are in hibernation for the duration of the winter meaning they don't wake up at all, others wake up every few weeks to have a snack and walk about before going back into hibernation. Home Range The area that an animal or group of animals lives in. Horn A hard, pointed growth on the head of some mammals. Incisor Tooth A flat tooth at the front of a mammal's jaw that is used for gnawing and slicing food. Incubation Period The incubation period is the time from when an animal egg is laid to when it hatches.

The term incubation period is used to refer to all egg laying mammals like fish, birds and reptiles but also to the platypus and the echidna which are the only egg laying mammals on earth.

The incubation period varies between animal species from the incubation period of a penguin egg which is around 60 days to the incubation period of the an iguana egg which is between three and four months. Insect Insects are invertebrate arthropods, which means that the insects body is made up of sections of shell rather than bones.

There are more than 1 million described species of insect found worldwide, but estimates suggest there to be around 30 million different species of insect still left to identify. Insects are found in every habitat around the world from the deserts, to the jungles and in the mountains.

Some species of insect also live in or around water such as the mosquito and the dragonfly. Insects generally have a lifespan that is less than a year, although some types of insects such as beetles, have been known to live for more than a few years. Internal Fertilisation Fertilisation that occurs inside the body of the female. Introduced Species A species that has been accidentally or purposefully been introduced, by humans, into an eco-system where it is not found naturally.

Keel An enlargement of the breastbone in birds, that secures the muscles during flight. Keratin A strong and resilient structural protein that is found in an animals hair, nails and horn. Kingdom A level of classifying all living things on earth, as similar species are broken into 5 groups including plants, animals and fungi. Larva A young insect that is independent of an looks very different from the adult form. Insect larva become adults through a metamorphic process.

Lifestyle Whether the animal is solitary or sociable [Top]. Litter Size The typical number of offspring an animal may give birth to at one time. Location The place in the world where something is found. For example, Chameleons can be found in forests in Madagascar. Mammal Mammals are warm blooded vertebrates that have mammary glands, which means that the females are able to produce milk to feed their young. Mammals are also the only animal group that gives bird to live young, where the others all lay eggs.

Mammals are generally land-dwelling animals but there are exceptions like the blue whale, which is the worlds largest mammal and grows to around 20 times the size of the biggest land mammal, the African elephant, average about 33 meters in length.. The smallest mammal in the world is the bumble bee bat which is only 3. There are approximately 5, different species of mammal found worldwide.

Mandible The paired jaws of an arthropod such as ants, crabs and spiders. Melon A large swelling of fatty-fluid that is found in the heads of many toothed whales, that is believed to improve sound focus used in echolocation. Metabolic Rate The rate of an animal's metabolism can be affected by many factors including size and energy. Metabolism A mixture of chemical processes that occur within the body of an animal to either release energy breaking down food or to consume it muscle movement.

Metacarpal The metacarpal is one of a set of bones that is found in either or the arm or the leg in all vertebrates with four limbs. Metamorphosis The complete change in body shape when certain animals move from being young animals into adults.

Metatarsal The metatarsal is one of a set of bones found in the back of the leg in all vertebrates with four limbs. Migration The migration of animals is generally connected with the seasons and involves with travelling between one place and another, often along a well-known route.

Mimicry When one animal attempts to camouflage itself by resembling another animal or an object such as a leaf or a stick. Molar Tooth A flattened or ridged tooth found at the back of the jaw in mammals, that is used for chewing. Mollusc Molluscs are a group of animals that are found in both marine and freshwater habitats.

The octopus and the squid are both molluscs. Monogamous Mating with a single partner for life or throughout the breeding season. Moult The shedding of fur, feathers, scales and skin so that it can be renewed and replaced. Name Of Young The name given to the offspring of an animal, for example a young Cat is called a Kitten. Natural Environment The term environment is used to describe everything in a certain area. This includes the terrain such as mountains and deserts, the natural elements that are found there like water and metal, the climate and all the living and non-living things in that area like animals, plants and objects.

Natural Selection The term natural selection refers to the the process where heritable traits that make it more likely for an organism to survive long enough to reproduce become more common over successive generations of a population.

This can include anything from the exterior appearance of an organism for example those that are most easily camouflaged tend to fair better to the temperament of an organism for example, a lion would have more difficulty in hunting prey if it was irrational and clumsy in behaviour instead of being stealthy and systematic in it's actions. Natural selection is a key mechanism of evolution. New World monkeys differ from other groupings of monkeys and primates, such as the Old World monkeys and the apes, mainly in the fact that New World monkeys tend to be small to medium in size.

The New World monkey group includes the world's smallest monkey, the pygmy marmoset. New World moneys are different from the Old World monkeys in many ways, including the fact that the nose of New World monkeys is flat and has side facing nostrils, the lack of opposable thumbs and due to the fact that most New World monkeys are arboreal, they often have prehensile tails.

Nocturnal If an animal is nocturnal it means that the animal tends to sleep during the daylight hours and wakes up to hunt when night falls. Raccoons, koalas and hedgehogs are all considered to be nocturnal animals. Nymph A young insect that is similar in appearance to it's parents but it does not yet have functioning organs or is able to fly.

Offspring An offspring is an animal's child or children. For example, a Kitten is the offspring of a Cat. Old World Monkeys The Old World monkeys are native to Africa and Asia today, inhabiting a range of environments from tropical rain forest to savannah, scrubland, and mountainous terrain, and are also known from Europe in the fossil record.

However, a possibly introduced free-roaming group of monkeys still survives in Gibraltar Europe to this day. Old World monkeys include many of the most familiar species of non-human primates such as baboons and macaques. Old World monkeys tend to be medium to large in size and tend to have a predominantly herbivorous diet preferring to eat plant matter rather than other animals.

Old World monkeys are known to have an opposable thumb and rarely have prehensile tails. Omnivore An omnivore is an animal that eats both plant material and other animals in order to get enough food. Animals that are omnivores have complex digestive systems that are able to deal with both plant animal material equally well, like kangaroos, otters and humans. Opposable Digits that are able to be pressed together from opposite directions, like thumbs in humans and apes.

Optimum pH Level The perfect acidity conditions for the animal. Order A level used to classify animals. Classes are broken into sub-groups known as order, which are broken down further into families. Organ A structure found in an animal's body that is made up of tissues and does a specific task. Organism In biological terms, an organism is used to describe a living thing whether animal, plant, fungi or micro-organisms.

Some organisms are single-celled organisms meaning that they consist of one cell that has a central nerve in the middle, for example bacteria. Other organisms are multi-celled organisms meaning that they consist of many cells all working together, for example humans. Origin The area where the animal first came from [Top]. Other Name s Different names which an animal may be called. Paratoid Gland A gland found behind the eyes of some amphibians that secretes poison onto the surface of their skin.

Partial Migrant An animal species where some individuals migrate but others don't. Pectoral Fin One of the two pairs of fins that are found at the front of the body of a fish.

Pelvic Fins The last pair of fins on the body of a fish, found on the underside, close to the tail. Pheromone A chemical produced by an animal which has an effect on animals from the same species but also on other animal species too. Photosynthesis The chemical process which plants use to create energy. Phylum A level of classifying animals within the animal kingdom.

Phylum are further divided into subgroups called classes. Placenta An organ that is produced by a developing animal that allows it to absorb nutrients from the mother's bloodstream when it is in the womb. Plankton Floating microscopic organisms that drift close to the surface of the sea in open water. Plant Types The typical types of plants which are found in a particular location.

Polygamous When male animals often made with several female animals throughout the breeding season. Predator When an animal is referred to as a predator, it means that the animal either hunts or catches other animals.

Predatory animals are generally dominant within their environment and will generally hunt animals smaller than themselves. Prehensile Prehensile is the term that is given the appendages of animals that have evolved to grasp or hold onto things.

For example, some species of monkey and most species of lizard have prehensile tails which allows them to hold onto tree branches with their tails so that they can reach down to collect food.

Most species of primates have prehensile hands and cats are known to have prehensile claws. The tongues of many animals are prehensile, particularly that of the giraffe. Elephants and tapirs are known to have prehensile noses, and horses and rhinos have prehensile lips.

Premolar Tooth A specialised tooth that is found about half-way along the jaw in mammals, that is often used for slicing through flesh.

Newsletter Signup