Jessica+Firkin


 * Biological Science – Expert Group Activity **

**__Mammals__**

 * **Hair** - Hair is one of the characteristics of a mammal that is unique to mammals—no other animals have true hair and all mammals have hair covering at least part of their body at some time during their life. An individual hair consists of a rod of cells that are reinforced by a protein known as keratin. Hair grows from skin cells called follicles. Hair can take on several different forms including thick fur, long whiskers, defensive quills or fearsome horns. Hair serves a variety of functions for mammals. It provides insulation, protects the skin, serves as camouflage and provides sensory feedback.
 * **Mammary glands** - Mammals nurse their young with milk produced by mammary glands. Mammary glands, like hair, are a uniquely mammalian trait. Though present in both males and females, in most mammal species mammary glands only fully develop in females. The exception to this rule is the male Dayak fruit bat, which has mammary glands that produce milk to feed its young. Mammary glands are modified and enlarged sweat glands that consist of ducts and glandular tissues that secrete milk through nipples. Young mammals obtain milk from their mother by feeding from her nipples. The milk provides the young with much needed protein, sugars, fat, vitamins and salts.
 * **Lower jaw made of a single bone** - Mammals differ from other vertebrates such as reptiles, birds and amphibians in that they have a single lower jaw bone that attaches directly to the skull. This bone is referred to as the dentary, due to the fact that it holds the teeth of the lower jaw. In other vertebrates, the dentary is one of several bones in the lower jaw and does not attach directly to the skull. The structure of the lower jaw and the muscles that control it provides mammals with a powerful bite and enables them to use their teeth to cut and chew their prey. Mammal species have specialized teeth adapted to their particular diet. Cats, for example, have sharp teeth that enable them to tear meat while herbivores such as bison have broad teeth, well-suited for grinding plant material.
 * **Diphyodonty** - Diphyodonty is a pattern of tooth replacement in animals in which the teeth are replaced only once throughout the lifetime. Young mammals have a set of teeth that are smaller and weaker than their adult teeth. This first set of teeth, also known as the deciduous teeth, fall out and are later replaced by a set of larger, permanent teeth.
 * **3 middle ear bones** - Mammals have a unique arrangement of three bones in the middle ear. These bones—the incus, malleus and stapes, commonly referred to as the hammer, anvil and stirrup—are unique to mammals, no other animal group has them. The middle ear bones transmit sound vibrations from the tympanic membrane or eardrum to the inner ear and transforms them into neural impulses. The malleus and incus are derived bones that were once part of the lower jaw in mammal ancestors.
 * **Endothermic** - Mammals are endothermic which means they are capable of regulating their own body temperature so that it remains at a relatively constant temperature regardless of the temperature of the surrounding environment.
 * **Diaphragm** - The diaphragm is a layer of muscle located at the base of the ribcage that separates the thoracic cavity from the abdominal cavity in mammals. Mammals are not the only vertebrates to posess a diaphragm, amphibians and reptiles also have diaphragms or diaphragm-like structures. It should be noted that the anatomy of the diaphragm and its position vary among the different classes of vertebrates.
 * **4 chambered heart** - Like all vertebrates (and even all animals with a circulatory system), mammals have a muscular heart that contracts repeatedly to pump blood throughout the body's blood vessels. The heart serves to deliver oxygen and nutrients throughout the body and remove waste products. In general, the heart consists of multiple chambers (the number of chambers differs for the various animal groups). Two to four chambers may be present and there are two types of chambers, the atrium and ventricle (the atrium receives the blood returning to the heart while the ventricle pumps blood from the heart to the rest of the body). The structure of a four-chambered heart offers greater efficiency than the three- and two- chambered heart structures. A four-chambered heart separates oxygenated blood coming from the lungs from the partially deoxygenated blood returning from the body to the lungs to be re-oxygenated. The prevention of mixing of these two streams of blood ensures that tissues receive oxygen-rich blood which in turn enables sustained muscle activity and helps in maintaining constant body temperatures.
 * **Tetrapod** - two sets of paired limbs.

**__Reptiles__**

 * **Scales** - Reptile skin is covered with scales, structures that grow on the animal's epidermis and consist of a hard substance known as keratin which is similar to human hair and fingernails. Scales are replaced periodically through a shedding process in which the entire skin is shed in one piece or flakes off in small pieces. Reptile scales vary in shape, size, texture and colour.
 * **Lay Eggs** - Hard-shelled eggs provide a protective environment in which the embryo can develop and enables reptiles to lay their eggs in dry environments.
 * **Lower jaw made of several bones** - several bones in their lower jaw that enable them greater bite mobility.
 * **Polyphydonty** - Polyphydonty, is a term used to describe the pattern of tooth replacement in which teeth are continuously replaced throughout the lifetime of an animal. Toothed fishes, reptiles and many other non-mammalian vertebrates are polyphydonts.
 * **Ectothermic** - cold-blooded animals. This means they are unable to regulate their own body temperature like birds and mammals do. Therefore, reptiles must modify their activity and behaviour to accommodate changing environmental temperatures. They must seek shelter during excessive heat (to prevent over-heating) and extreme cold (to prevent hypothermia). But being cold-blooded has its advantages too. It has enabled reptiles to enjoy success in habitats that mammals and birds find challenging. Since reptiles do not need to burn calories to fuel a constant body temperature, they can survive on much less food intake that birds and mammals. For this reason, reptiles are the dominant vertebrate in desert habitats.
 * **One bone in each ear** - the stapes
 * **Tetrapod** - Reptiles are considered as tetrapods with two sets of paired limbs. Most of these animals have five clawed toes on each limb. These muscular appendages are angled downward to facilitate faster locomotion. In some reptiles, the legs are absent.
 * **3 chambered heart** - All reptiles have three-chambered hearts, except crocodiles, which have four-chambered hearts (2 atria, 2 ventricles), like mammals and birds. The three chambers in reptiles consist of two atria to receive blood and one partially divided ventricle for pumping blood.

**__Week 1 - Sexual/Asexual Reproduction__**
__**Sexual Reproduction **__ Sexual reproduction occurs when two individuals produce an offspring. The offspring with have genetic characteristic or shared DNA from both parents. Sexual reproduction in plants involves main two processes – //pollination// and //fertilization//.
 * Sexual reproduction in a plant: **
 * Pollination is when the male gamete (pollen) contained in the anther of the stamen (male part of the flower) is transferred to the stigma of the pistil (female part of the flower). Cross-pollination occurs when the pollen from one plant is transferred to the stigma of another plant.
 * Fertilization occurs when pollen trapped by the stigma germinates to produce a long tube which travels down the style and enters the ovary. The pollen in the long tube (containing the male gamete) fuses with the female gamete in the ovule (contained inside the ovary). The zygote (fertilized cell) then matures in the ovary to become a seed. The seed then grows to produce a new plant.



The following image shows the lifecycle of a sexually reproductive plant:



Plant Reproduction: []

**__Asexual Reproduction __**
Asexual reproduction does not require two individuals to reproduce. The offspring are genetically identical to the parent. There are different types of asexual reproduction at the organism level these can include budding, fragmentation and parthenogenesis.
 * //Budding //** refers to offspring that develop on the parent that then break away and become independent.
 * //Fragmentation //** refers to when part of the adult breaks up, that part can then mature and become an adult. The cycle can then be repeated.
 * //<span style="font-family: 'Arial',sans-serif;">Parthenogenesis //**<span style="font-family: 'Arial',sans-serif;"> refers to when a female produces an egg that does not require fertilization from a male to develop.



<span style="font-family: 'Arial',sans-serif;">An example of asexual reproduction: <span style="font-family: 'Arial',sans-serif;">1. The hydra develops a "bud". <span style="font-family: 'Arial',sans-serif;">2. The bud develops a mouth and tentacles <span style="font-family: 'Arial',sans-serif;">3. When it is fully formed the daughter hydra detaches from its parent. <span style="font-family: 'Arial',sans-serif;">4. The daughter hydra is now fully independent.

//<span style="font-family: 'Arial',sans-serif;">“Komodo dragons, hammerhead sharks, Brahminy blind snakes, water fleas, certain types of bees, scorpions, wasps, and even some types of birds, among others, are capable of reproducing asexually, if necessary”. // <span style="font-family: 'Arial',sans-serif;">Female Komodo dragons (the largest lizard) can produce offspring by parthenogenesis when no male is available for sexual reproduction. Their offspring are homozygous at every locus including having identical sex chromosomes. Thus the females produce all males because, unlike mammals, females are the heterogametic sex (ZW) while males are homogametic (ZZ).

//<span style="font-family: 'Arial',sans-serif;">Interesting: //<span style="font-family: 'Arial',sans-serif;">[] <span style="font-family: 'Arial',sans-serif;">Asexual reproduction: []


 * __<span style="font-family: 'Arial',sans-serif; font-size: 16px;">Differences between sexual and asexual reproduction __**
 * **<span style="font-family: 'Arial',sans-serif;">Sexual ** ||  **<span style="font-family: 'Arial',sans-serif;">Asexual **  ||
 * <span style="font-family: 'Arial',sans-serif;">Two parents: male + female || <span style="font-family: 'Arial',sans-serif;">One parent: male or female ||
 * <span style="font-family: 'Arial',sans-serif;">Genetically different to parent || <span style="font-family: 'Arial',sans-serif;">Genetically identical to parent ||
 * <span style="font-family: 'Arial',sans-serif;">Advantages: offspring will be different from parent, better at adapting || <span style="font-family: 'Arial',sans-serif;">Advantages: quick, efficient if suited to the environment, populate faster ||
 * <span style="font-family: 'Arial',sans-serif;">Disadvantages: slower process, less population || <span style="font-family: 'Arial',sans-serif;">Disadvantages: Slow to adapt if the environment changes ||

__Week 2 - Adaptation__
<span style="font-family: 'Arial',sans-serif; font-size: 16px;">Adaptation is the process by which creatures adapt to their habitat. Those with the most suitable characteristics survive to breed. Creating creatures fitted to their habitat. <span style="font-family: 'Arial',sans-serif; font-size: 16px;"> Fish, ladybeetles, butterflies and peacocks have spots. But these spots are not for camouflage purposes: they are bright colourful spots easily seen by predators. //Why? Is this a problem or an advantage?// (Loxley, 2010)
 * __<span style="font-family: 'Arial',sans-serif; font-size: 16px;">Adaptation __**
 * <span style="font-family: 'Arial',sans-serif; font-size: 16px;">Consider the following: **
 * <span style="font-family: 'Arial',sans-serif; font-size: 16px;">Colourful spots are often used to attracted the opposite sex and therefore increase the chance of reproduction within different species.
 * <span style="font-family: 'Arial',sans-serif; font-size: 16px;">Spots can often be used as a defense mechanism to scare of predators that may think they are poisonous or inedible.

**<span style="font-family: 'Arial',sans-serif; font-size: 16px;">Cheetah (Acinonyx jubatus) ** <span style="font-family: 'Arial',sans-serif;">The fastest land mammal in the world, the cheetah (Acinonyx jubatus) has many adaptations that allow it to sprint across the plains; the rangy frame supports long limbs and a deep chest cavity, together with a small waist and an extremely flexible spine. Unlike other cats, the cheetah’s claws are not fully retractable, and provide additional grip on the ground during a hunting sprint. The large nostrils allow greater amounts of air to enter the lungs, and the tail is particularly long to provide extra balance when cornering. <span style="font-family: 'Arial',sans-serif;">The common name of this species is derived from the Hindi word chita meaning ‘spotted’ or ‘sprinkled’. The coat of the cheetah is a yellowish, tan or tawny colour with black spots on the upperparts, and a paler, whitish colour on the underpart. The last third of the tail has a series of black rings.

**<span style="font-family: 'Arial',sans-serif; font-size: 16px;">Lemur leaf frog (Agalychnis lemur) ** <span style="font-family: 'Arial',sans-serif; font-size: 14.6667px;">A highly threatened amphibian from Central America, the lemur leaf frog (//<span style="font-family: 'Arial',sans-serif;">Agalychnis lemur //) has a remarkable ability to change colour depending on whether it is active or resting. <span style="font-family: 'Arial',sans-serif; font-size: 14.6667px;">When resting during the day, the slender lemur leaf frog is mostly bright green, speckled with small brown dots. Its hands, feet and flanks are yellow and its underparts are white. A thick black line surrounds each large, pale, pearly eye. The vertical pupils indicate the lemur leaf frog’s nocturnal lifestyle. <span style="font-family: 'Arial',sans-serif; font-size: 14.6667px;">When active during the night, the upperparts of the lemur leaf frog turn brown, thus providing excellent camouflage. Its eyes also turn dark grey. Individuals from different areas differ slightly from each other.

<span style="font-family: 'Arial',sans-serif; font-size: 16px;">Both of these animals have adaptations that allow them to be best suited for their habitat/environment.
 * <span style="font-family: 'Arial',sans-serif; font-size: 18.6667px;">How is it an adaptation? **