Viva Education Class 9 Biology Pdf

[Lynn Hepler]

Thefirst amniotes evolved from amphibian ancestors approximately 340 million years ago during the Carboniferous period. The early amniotes diverged into two main lines soon after the first amniotes arose. The initial split was into synapsids and sauropsids. Synapsids include all mammals, including extinct mammalian species. Synapsids also include therapsids, which were mammal-like reptiles from which mammals evolved. Sauropsids include reptiles and birds, and can be further divided into anapsids and diapsids. The key differences between the synapsids, anapsids, and diapsids are the structures of the skull and the number of temporal fenestrae behind each eye (Figure). Temporal fenestrae are post-orbital openings in the skull that allow muscles to expand and lengthen. Anapsids have no temporal fenestrae, synapsids have one, and diapsids have two. Anapsids include extinct organisms and may, based on anatomy, include turtles. However, this is still controversial, and turtles are sometimes classified as diapsids based on molecular evidence. The diapsids include birds and all other living and extinct reptiles.

In the past, the most common division of amniotes has been into the classes Mammalia, Reptilia, and Aves. Birds are descended, however, from dinosaurs, so this classical scheme results in groups that are not true clades. We will consider birds as a group distinct from reptiles for the purpose of this discussion with the understanding that this does not completely reflect phylogenetic history and relationships.

One of the key adaptations that permitted reptiles to live on land was the development of their scaly skin, containing the protein keratin and waxy lipids, which reduced water loss from the skin. This occlusive skin means that reptiles cannot use their skin for respiration, like amphibians, and thus all breathe with lungs.

Reptiles are ectotherms, animals whose main source of body heat comes from the environment. This is in contrast to endotherms, which use heat produced by metabolism to regulate body temperature. In addition to being ectothermic, reptiles are categorized as poikilotherms, or animals whose body temperatures vary rather than remain stable. Reptiles have behavioral adaptations to help regulate body temperature, such as basking in sunny places to warm up and finding shady spots or going underground to cool down. The advantage of ectothermy is that metabolic energy from food is not required to heat the body; therefore, reptiles can survive on about 10 percent of the calories required by a similarly sized endotherm. In cold weather, some reptiles such as the garter snake brumate. Brumation is similar to hibernation in that the animal becomes less active and can go for long periods without eating, but differs from hibernation in that brumating reptiles are not asleep or living off fat reserves. Rather, their metabolism is slowed in response to cold temperatures, and the animal is very sluggish.

Although they are sometimes mistakenly called dinosaurs, the pterosaurs were distinct from true dinosaurs (Figure). Pterosaurs had a number of adaptations that allowed for flight, including hollow bones (birds also exhibit hollow bones, a case of convergent evolution). Their wings were formed by membranes of skin that attached to the long, fourth finger of each arm and extended along the body to the legs.

The dinosaurs were a diverse group of terrestrial reptiles with more than 1,000 species identified to date. Paleontologists continue to discover new species of dinosaurs. Some dinosaurs were quadrupeds (Figure); others were bipeds. Some were carnivorous, whereas others were herbivorous. Dinosaurs laid eggs, and a number of nests containing fossilized eggs have been found. It is not known whether dinosaurs were endotherms or ectotherms. However, given that modern birds are endothermic, the dinosaurs that served as ancestors to birds likely were endothermic as well. Some fossil evidence exists for dinosaurian parental care, and comparative biology supports this hypothesis since the archosaur birds and crocodilians display parental care.

Class Reptilia includes many diverse species that are classified into four living clades. These are the 25 species of Crocodilia, 2 species of Sphenodontia, approximately 9,200 Squamata species, and the Testudines, with about 325 species.

The amniotes are distinguished from amphibians by the presence of a terrestrially adapted egg protected by amniotic membranes. The amniotes include reptiles, birds, and mammals. The early amniotes diverged into two main lines soon after the first amniotes arose. The initial split was into synapsids (mammals) and sauropsids. Sauropsids can be further divided into anapsids (turtles) and diapsids (birds and reptiles). Reptiles are tetrapods either having four limbs or descending from such. Limbless reptiles (snakes) are classified as tetrapods, as they are descended from four-limbed organisms. One of the key adaptations that permitted reptiles to live on land was the development of scaly skin containing the protein keratin, which prevented water loss from the skin. Reptilia includes four living clades: Crocodilia (crocodiles and alligators), Sphenodontia (tuataras), Squamata (lizards and snakes), and Testudines (turtles).

The chorion facilitates the exchange of oxygen and carbon dioxide gases between the embryo and the surrounding air. The amnion protects the embryo from mechanical shock and prevents dehydration. The allantois stores nitrogenous wastes produced by the embryo and facilitates respiration.

The most defining element of the Duke in Spain program is its complete immersion of students into the madrileo culture. Our final project for our arts and literature class involved visiting a slam poetry bar and presenting a reflection of our experiences to the class. My group visited the Aleatorio, a cozy slam poetry bar tucked away a few blocks from the Duke in Madrid center.

That night there were no traditional reading programmed; instead the audience ran the program. We were given a starting phrase and five songs worth of time to write a short story to present. As an American visitor to this local poetry bar, I felt completely out of my element. Creative writing, on the spot, in my second language, presented to strangers- home definitely felt 4,000 miles away.

This program has inspired me to pursue a major in Spanish and I am looking forward to volunteering with the Spanish speaking community in Durham this semester in order to continue learning Spanish through stepping outside my comfort zone. Duke in Spain is an amazing program if you want to learn Spanish in a challenging, yet incredibly rewarding way.

"After a day of seeing the Terracotta Warriors, watching a Tang dynasty performance, and eating way too much food, I somehow found myself energized to visit the night market near our hotel in Xian."

"The highlight of my experience in Costa Rica was the quality of the time I spent learning with my classmates and professor. Going on a study abroad in a small group really allows you to learn in depth and in unison."

My particular career interests in entertainment have become clearer. I now know that I want to focus on diversity and inclusion as a president or vice president of a corporate entertainment organization."

"I observed the daily telephone conversations between my host mom and her daughters; the locals walking and holding hands; the students at the University of Alicante offering to hang out despite their exams."

"I was excited by the prospect of immersing myself within the city in an academic setting. The focus on internships seemed to be a perfect match for my interests in the writing and media industries."

"My favorite part of this experience was really all of it. I especially loved the daily excitement and the constant learning and exploring. I loved living in Alicante, a small, compact city on the Mediterranean. I loved living with my host mom, a feisty, energetic woman who cared for me deeply despite the language barrier."

Prior to the Duke in Spain program, I didn't have a lot of experience reading or writing in academic Spanish. The program allowed me to improve these areas through literary, historical and artistic angles."

"Participating in a study abroad experience before I graduated was important to me. I really enjoy learning about different cultures and going to Australia provided me with the opportunity to do just that."

"I realized how much I liked Italian culture on this trip, so I actually signed up for more Italian classes to fulfill an Italian major while I was studying in Bologna. Bologna is a decently tourist-free city, so I felt that I was really immersed in Italian culture."

"The program does an amazing job matching students with families for the homestay! My host mom worked in a field similar to the one I would like to go into, and I was able to learn not only the French language, but also about what was happening in France that related to my interests."

Moving to Geneva for six weeks was certainly outside of my comfort zone. I went into the program without knowing anyone else who was doing it. As a result, the Duke in Geneva program helped me become more independent and self-confident."

One thing that really surprised me about the spring program, even after completing the summer program, is how independent I became in Berlin. By the spring I felt much more like a resident of Berlin, instead of a Duke student on study abroad."

This program confirmed my interest in working on the human rights side of migration. Advocating for and finding solutions to protect economic, social, and cultural rights is what I plan to pursue in my long-term career."

This program was part of the reason why I decided to make global health a second major. I was originally going to minor in it, but thanks to courses at Duke and this experience abroad, I realized I loved global health and global development enough to add another major."

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