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Warming and coolingEndothermic animals use different warming and cooling mechanisms in response to the environment.

Response to high temperature Response to low temperature

Vasodilation: Arterioles dilate, which allows more blood to enter the capillaries in the skin.

Vasoconstriction: Arterioles constrict, so less blood flows to the skin.

Pilorelaxation: Pilli erector muscles relax which lowers the hairs/feathers on the skin so that air can circulate. This allows for convection and evaporation.

Piloerection: Pilli erector muscles contract causing hairs or feathers on the skin to be raised. This traps a layer of insulating air, reducing heat transfer from the skin. Moulting can also help.

Sweating: Glands secrete sweat onto the skin, where it evaporates and takes heat from the body. Adrenal and thyroid glands secrete adrenaline and thyroxine which reduces metabolic rate and therefore heat generation. Gular fluttering: Increases heat loss through the mouth. It occurs in birds, where they rapidly flap membranes in the throat to increase evaporation.

Shivering: Muscles contract and relax rapidly and cause heat to be produced by friction and respiration.

Panting: Panting is the process of evaporation of water from within the nasal passages, mouth, lungs, and (in birds) air sacs. This method of cooling is used by many mammals, reptiles and birds.

Brown adipose tissue (BAT): Cells take lipids and run them through the mitochondria to generate heat. BAT is present in almost all mammals and is found in greater quantities in neonates and hibernating mammals.

Behavioural changes: Stretching out the body gives a larger surface area for heat loss. Animals may seek shade and move less.

Behavioural changes: Curling up causes a smaller surface area for heat to escape. Animals may move to warmer areas and show increased movement.

Metabolic rateEndotherms can adjust their metabolic rate to regulate their internal body temperature. Metabolic reactions give off heat, so animals can alter their internal body temperature by changing their metabolic rate. Ectotherms cannot use this mechanism on their environment.

Countercurrent mechanismSome animals have developed a countercurrent mechanism to control heat regulation. Heat is exchanged between two sources flowing in opposite directions. In heat regulation, these flowing sources are the bloodstream. When the body temperature drops, arteries carry warm oxygenated blood away from the heart while veins carry cold deoxygenated blood towards the heart. As these two pass, the warm arterial blood transfers most of its heat to the cool venous blood and body temperature is balanced.

Sweating, gular fluttering and panting are all evaporative cooling mechanisms.

Extremes of temperatureIf an animal is exposed to extreme external temperature changes, this can result in hypothermia or hyperthermia.Hypothermia: the body cannot maintain normal body temperature. There are three phases. Symptoms will depend on the phase. Mild symptoms include weakness, shivering and lack of alertness. Moderate symptoms include muscle stiffness, low blood pressure and slow breathing. Severe symptoms include fixed or dilated pupils, inaudible heartbeat, difficulty breathing and coma. Hypothermia can result in death.

Hyperthermia: is the elevation of the body temperature above the normal. Fever hyperthermia results from inflammation within the body (e.g. due to infection). Non-fever hyperthermia results from all other causes of increased body temperature (e.g. excessive exercise, excessive levels of thyroid hormones). Symptoms include: panting, dehydration, reddening of the gums, decease of urination, uncoordinated movements and unconsciousness. It can lead to multiple organ dysfunction and death.

What is the effect of vasoconstriction?

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Adaptation and variationAdaptations to different environments occur over many generations, through variation.

AdaptationsAdaptations can be physiological, behavioural and anatomical and can be a result of an animal’s lifestyle, diet and/or environment. • Physiological – adaptations

in an animal’s body processes, for example, some snakes are physiologically adapted to produce venom which they use in defence against predators.

• Anatomical – adaptations in an animal’s shape and structure, for example, the bat forelimb has become adapted to form wings, improving their access to suitable food sources.

• Behavioural – adaptations in an animal’s language, tool use and survival strategies, for example, migration in some bird species to avoid harsh environments.

Selection pressures on variationThere are different types of selection pressures that affect variation:

Stabilising selection pressure that reduces variation between animals’ DNA. Extreme phenotypes are reduced, and the proportion of animals with the average phenotype is increased.

Directional selection pressure that encourages a particular new phenotype, usually in response to environmental changes.

Diversifying/disruptive selection pressure that increases variation between animals’ DNA. Extreme phenotypes become more common and average phenotypes are reduced.

VariationsVariation is the differences between organisms. It can include variations in diet, behaviour and aesthetics. Variation between animals is linked to differences or changes in the DNA. Because of this, variations can be passed on from parents to their offspring, i.e. they are heritable. Some variations give an animal an advantage over other animals, for example, being able to run for longer, reach higher branches or have better camouflage. Animals with an advantageous variation are more likely to survive and therefore more likely to reproduce. Because the variation is heritable, their offspring are likely to have the advantageous feature, increasing their chance of survival too. This is natural selection. Over time, this can lead to evolution of a species. If animals in a species develop different variations which both give them advantages, it could lead to the species separating into two species; this is called speciation.

Red crabs migrate once a year to their breeding ground on the beach.

State the type of adaptation this shows.

DefinitionsEvolution – a change in characteristics over several generations.Speciation – the formation of a new species as part of the evolutionary process.

Polar bear adaptationsLarge feet with fur on the soles improves grip

on the ice.

Small surface area to volume ratio and small ears reduce heat loss.

Strong legs help catching their prey when swimming and running.

Thick layer of adipose under the skin for insulation and energy.

Thick white fur for insulation and camouflage.

Sharp teeth and claws for feeding and defending.

Pregnant females hibernate.

Highly developed sense of smell and hearing.

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indri squirrel monkey

lesser andgreater apes

(no tails)

haplorrhines‘dry nose’

catirrhines‘narrow-nose’

baboon chimpanzee

human

strepsirrhines‘wet nose’

platyrrhines‘flat-nosed’

old worldmonkeys (tails)

63 millionyears ago

40 millionyears ago

25 millionyears ago

5 millionyears ago

modernday

lemur marmoset

Modern technology and classification

Unlike the binomial system of naming species using Latin names, cladistics looks at data from DNA and RNA sequences, not just physical characteristics.

CladisticsCladistics looks at an evolutionary relationship between species, not just physical traits. In order for species to be grouped, they must all:

share a common ancestor.

be included in the same taxon (group).

A cladogram emphasises the genetic relationship between species.

Analysing how animals are relatedThere are different ways to analyse how animals are related.

Genetics: Use of DNA sequencing to provide information on how species are genetically related and their evolutionary lineage. Comparison of DNA-based sequences can be carried out by:• DNA sequencing: looks at a species’

proteins (which are coded for by their DNA). Species that are more closely related will have more similar DNA and proteins than distantly related ones.

• DNA hybridisation: looks at how similar DNA is without sequencing it. It involves looking at hydrogen bonds and the amount of heat needed to break them. The higher the temperature, the more closely related the species are.

Biochemical: looks at the substances found in living organisms and the processes occurring within these organisms.

Immunological comparisons: analyses antibodies binding to proteins and antigens in different species and if they are recognised. More similar species will have more recognition between their antibodies and antigens.

Amino acid comparisons: looks at the amino acids formed by the species and the nucleotide sequences they utilise to form the amino acids.

This primate cladogram shows that marmosets are closely related to squirrel monkeys, and that approximately 25 million years ago, lesser and greater apes were speciated from old world monkeys.

1 Explain what information is needed to produce a cladogram.

You are working in a laboratory looking at the genetic relationship between two aquatic species. The process you are asked to use involves the use of heat.

2 State what process you are going to use.

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Kingdom

Phylum

Class

Order

Family

Genus

Species

Grouping organismsTaxonomy is a way of classifying living things based on the similarities and differences between them. There are seven levels or steps of classification, from general to specific. Different characteristics are assessed at each level, and organisms with similar characteristics are grouped together.

Living organism classificationAnimals can be classified into groups so that they can be identified. It also allows scientists to study the relationships between organisms.

Characteristics of the five vertebrate classes Pisces: gills, wet scales, ectothermic

Reptilia: dry scales, egg laying, ectothermic

Amphibia: egg laying, moist skin, ectothermic

Aves: egg laying, feathers, beaks, endothermic

Mammalia: live bearing, milk producing, endothermic

Kingdom is the least specific level of classification, species is the most.

This classification system can be abbreviated to: K P C O F G S system.

1 Name two kingdoms other than Fungi, Plantae and Protoctista.

2 Write down the seven steps of animal classification.

Example: Taxonomy of the dogThis example shows the taxonomy of the dog, Canis lupis. A phylogenetic tree shows how closely related the organisms are. It shows that some species share a common ancestor: the ancestor, and all its descendants, are together known as a clade.

Kingdom categoriesThe kingdom level is divided into categories:Animalia (all multicellular animals)Plantae (multicellular, all green plants)Fungi (multicellular, moulds, mushrooms, yeast)Prokaryotae (usually unicellular with no nucleus, e.g. bacteria, blue-green algae)Protoctista (unicellular with a nucleus, e.g. Amoeba, Paramecium).

Binomial namesEvery organism is given two Latin names (the Binominal System): • genus (upper-case first letter) • species (lower-case first letter). For example, Ursus maritimus is the binomial name for a polar bear.

order family genus species

pantherataxidea

lutracanis

felidaem

ustelidaecanidae

carnivora

Pantherapardus

Taxideataxus

Lutralutra

Canislatrans

Canislupus

Kingdom Animalia

Phylum Chordata

Class Mammalia

Order Carnivora

Family Canidae

Genus Canis

Species lupis

A species is a group of animals with similar characteristics which can interbreed to produce fertile offspring.

Note the binomial name is written in

italics. If handwritten, then underlined.

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Classification difficultiesClassification difficulties can occur in unusual mammals, for example, the armadillo, bat, duck-billed platypus, whale and pangolin.

ArmadilloKingdom AnimaliaPhylum ChordataClass MammaliaOrder CingulataFamily Dasypodidae

Armadillos’ outer ‘armour’ is made from specialised bone covered in small overlapping scales made from epidermal tissue. Even though it looks like those within the Reptilia class, an armadillo is actually a mammal.

Duck-billed platypusKingdom AnimaliaPhylum ChordataClass MammaliaOrder MonotremataFamily OrnithorhynchidaeGenus Ornithorhynchus Species Anatinus

The duck-billed platypus has many characteristics of the Aves class: it has webbed feet and gathers its food underwater. The females lay their eggs in burrows. Around 10 days later, the eggs hatch and the mother will care for them until they are able to swim on their own. There are only five mammal species within the Monotremata order.

Other taxonomic strategies The K,P,C,O,F,G,S system of classification looks at the homologous features between animals to determine common ancestry. An alternative system is to look at analogous features which look similar but does not mean the animals have a similar ancestry.

WhaleKingdom AnimaliaPhylum ChordataClass MammaliaOrder Cetartiodactyla

Whales are mammalia which live in the sea, as opposed to the Actinopterygii class. They are warm blooded and have a four chambered heart, unlike fish which have a two chambered heart.

PangolinKingdom AnimaliaPhylum ChordataClass MammaliaOrder PholidotaFamily Manidae

BatKingdom AnimaliaPhylum ChordataClass MammaliaOrder Chiroptera

Although bats are within the mammalian class, they have some characteristics of the Aves class. Bats are the only mammals capable of true flight (not gliding). Unlike birds, their wing structure is maintained by the phalanges which move to move the wing. Bats are also split into different family groups.

Armadillos have a feature which is not commonly associated with mammals.

Describe this feature and identify which groups of animals this is most often associated with.

A pangolin

Pangolins are within the mammalian class, although they have similar characteristics to the Ava and Reptilia classes. They are covered in keratin scales and their stomach also has keratinised spines, which project inwards and often contain stones. This helps to grind the food in a similar way to a bird’s gizzard.