Unit 1 Main Ideas - Notes on Diversity of Living Things

Topic 1 Diversity and AdaptationTopic 1 Diversity and Adaptation

Why do species have the shape and structures they do? Adaptations are features that help plants and animals survive and reproduce in their environment. These adaptations include the organism’s behaviour, internal structures, life cycle, and external appearance.

How do we make sense of the great diversity we see around us?We look at structure. By sorting organisms with similar structures into groups and then comparing groups we can test the idea that each organisms appearance is related to a particular environment and way of life. This leads us to the idea of a species- in which all organisms of the same species have a very similar set of adaptations and they reproduce only among themselves.

Why is there diversity among the species itself and what exactly are these differences?Some variation within a species is normal and to be expected. We need to observe closely so that the differences we observe mean that we are differentiating between two species or one species at a different part of its life cycle. For example, frogs, june beetles, and dragonflies undergo such great change during their lives that we might mistake this for two different species! This change or growth is called metamorphosis. (Meta meaning change of and morph meaning form). A memorable example of this is the life cycle of a butterfly. It goes from egg to larva to pupa to adult with wings.

Another important idea here is the idea of sexual dimorphism. This is the difference in appearance between the sexes. An example is the fact that in peafowl the hen is very drab coloured while the male is a brilliant green and blue with large bright feathers or the paper nautilus – the female is nearly ten times larger in size.

Polymorphism is the existence of several forms of the same species. For example social insects such as termites and ants have soldiers, workers, kings, and queens all with different forms.

Who Cares, So What, or Why is this Important?These variations within species are important because they allow the organism a

greater chance for survival and reproduction. We here among the living believe this is a good thing..

Go to the internet. Find an unusual plant or animal that you would like to find out more about. Print out a picture of it. You may have to go to another printer. Mount it on a paper. Label the structures. Follow the directions in your book. This is due at the beginning of next class. You will have no other class time to work on it. This will be graded and worth about 10 % of your mark.

Topic 2 Reproduction and Survival

Is there more than one method of reproduction? Why is this important?Yes there is more than one method of reproduction. Asexual

reproduction can occur in a variety of ways. Hydras are able to reproduce by budding. This simple animal creates more of itself by growing new buds. Each new bud is an exact copy of its parent. Spider plants send out new runners that do the same thing. An advantage of this process is speedy reproduction.

Most organisms though, reproduce by sexual reproduction. This process requires two parents. The advantage here is the huge potential for variation among the offspring. Each parent produces special reproductive cells called gametes. These are sperm from the males and eggs from the females. When the sperm and egg unite they are called a zygote. The gametes combine at fertilization.

What are traits and what do they tell us about inheritance, genes and sex?Traits are characteristics that we inherit from our parents. Examples

are hair, skin and eye colour. Exercise 5-3 on p 235 is an example. Science has shown that we get these traits from the cells contributed by our parents. Inside each gamete are units called genes.These genes are the instructions that control the development of the inherited traits. Studies on inheritance have shown that genes have two or more forms called alleles. Many different combinations of alleles are possible in each offspring. For example a male and female with only 100 traits could produce more than 1 X 10 30 different combinations among their offspring. This is the huge advantage of sexual reproduction.

What is Artificial Selection?Artificial selection is the process whereby farmers choose which plants or animals they want to breed. By using this form of selective breeding i.e. choosing the best stock, the offspring are more likely to be healthy. An example is Marquis wheat developed on the Canadian Prairies. A disadvantage to this is that some genetic problems may occur. Certain breeds of dogs such as Pekinese for example have breathing problems.

Topic 3 How Species ChangeTopic 3 How Species ChangeDo species change? We have learned that members of a species are not all the same. Variations in the traits of an organism allow some to be more successful than others in surviving and reproducing another generation. The Case of the Peppered Moth is an example.Before 1848 in England, every peppered moth that biologist had observed had light coloured wings. After this time people started noticing more dark coloured wings. By 1898, dark coloured winged moths outnumbered the light coloured moths in some areas by a ratio of 99 to 1. Why? During this period, the tree trunks where the moths slept changed colour due to the industrial pollution. The well camouflaged moths had a greater likelihood of not being noticed by the predatory birds that fed upon them. The pollution had made the light trees dark. As the environment changed so did the likelihood of survival individuals who remained camouflaged with their surroundings.

What is the Theory of Natural selection?The process that produced the change in the peppered moth population is called natural selection. Alfred Russel Wallace and Charles Darwin both came up with this theory at the same time. There are 3 main observations that led them on. These are:

1) there is variation in traits among the individuals in a species, 2) individuals pass on forms of traits to their offspring by reproducing, and 3) not all individuals reproduce.

A point worth noting is that whether a trait is helpful or harmful to an organism depends not only on the trait itself, but also on the organism’s environment. For example, is it advantageous to be a tall plant or a short one. The tall trait allows the plant to get more sunlight. This also means wind may damage the plant more. A trait of shortness will help the plant withstand wind damage, however, it may be shaded more easily. Sometimes a trait may not seem to make any difference in an organism’s survival. If the environment changes quickly a form of trait that once made little difference may suddenly save its life. Rice for example has over 60,000 traits – because it is a rooted plant it must withstand many different conditions.How and Why do New Species Appear?Remember that a species may be defined as a group of organisms that can interbreed with one another. In nature, the members of a species do not have an equal chance of breeding with all other members of their species. Organisms tend to live in distinct populations that may have little contact with each other. Over time the distinct populations become more and more distinct. Consider the blind cave fish. In a dark environment, there is no advantage to having eyes. The energy used for sight may be used in other ways. Eventually the entire population is blind!Relationships Among Different SpeciesEvidence from populations in the wild has shown that different species can in fact mate with each other. Zebras and horses have mated and produced offspring. Lions and tigers are another example. Horses and donkeys are often cross- bred to produce mules. On the basis of similarities and differences in appearance and behaviour we may see clues to the genetic relationships. On the basis of resemblances among them, different species can be grouped into families. This will be our next topic of study.

Topic 4 Classifying Living ThingsWhat characteristics should we use to sort living things?Most scientists now divide all living things into 5 major groups called Kingdoms. They are 1)Prokaryotae, 2)Protista, 3)Fungi, 4)Plantae, and 5)Animalia. 1). Prokaryotes are single celled organisms that may be singular or live in colonies. (pro means before and karyon means nucleus – meaning these bacteria do not have a nucleus.) 2). Organisms classified as protista on the other hand do have a cell nucleus and other cell structures. They may be either unicellular or multi-cellular. They include paramecium, amoeba, stentor, volvox, euglena, actinosphaerium, and didinium.3). Fungi too may be either uni or multi-cellular. Fungi are not grouped with plants because they are not capable of photosynthesis. Fungi obtain their food from other organisms and they digest this food outside themselves and then absorb it through their thick cell walls called chitin. There are about 100,000 species of fungi.4). Organisms classified as plantae are multi-cellular and they are able to make their own food by photosynthesis. A defining characteristic of this group is the rigid cell wall around each cell.5). Organisms classified into the group we call animalia have a number of characteristics which include the facts that they are dependent on other organisms for food, their cells are bound by flexible membranes only, and most are capable of locomotion.

What is the hierarchical system we use today? (KPCOFGS)The 7 major levels in the classification used by biologists today are: Kingdom, Phylum, Class, Order, Family, Genus, SpeciesTable 5-4 An Example of Hierarchical ClassificationLEVEL EXAMPLE SOME ANIMALS INCLUDED IN THIS LEVEL

Kingdom Animalia earthworm horse lynx tiger house cat bobcat dog lizard

snail Phylum Chordata horse lynx tiger house cat bobcat dog lizard

Class Mammalia horse lynx tiger house cat bobcat dog Order Carnivora lynx tiger house cat bobcat dog Family Felidae lynx tiger house cat bobcat Genus Felis tiger house catSpecies Felis domesticus house cat

..—ilsl

Who was Linnaeus, and what was the two name system?A Swedish scientist Carl von Linné, came up with the two name system using Latin since Latin was the language of learning used in many different countries. The first word in the system is the genus in which the animal is classified. It is always capitalized. The second name – the species name is never capitalized. By giving an organism a scientific name, anyone, anywhere can use it for speaking or writing about the organism.

What is the usefulness of a classification system?Simply, it allows scientists to communicate about species without confusion and to identify the relationships between species. Sharks, Icthyosaurs, and porpoises may seem at first glance to be similar, however, as we look at their deep structures we find they are very different.

What are the Keys to Identification?Biologists use a key to discover which group and species an unknown organism belongs to. This key is a checklist that describes various characteristics an organism may or may not have. A dichotomous key is a list of alternatives arranged so that you can track down the group to which an organism belongs.

How does a dichotomous key work?To use a dichotomous key, begin with the first choice and read both descriptions at that number. At the end of the description will be either a number that leads you to another pair of alternatives, or the name of the organism. If you find the name of the organism, then you have identified it and you need go no further in the key. If you find a “go to” statement, continue with further choices as indicated.

How do we make a Dichotomous Key?

Topic 5 Similarities and Differences Among PlantsWhat are the major groups that plants are classified into and What are the differences in Structure?All plants are autotrophs- they make their own food by photosynthesis. 1).The simplest plants are mosses and liverworts. They are classified in the phylum Bryophyta. Bryophytes have no roots or vascular tissue to transport water. As a result they need to live in wet or moist areas. Bryophytes are able to reproduce asexually by releasing spores. They also reproduce sexually when there is sufficient water to allow the sperm to swim to fertilize an egg cell. If conditions are too dry, the plant becomes dormant.2) The next type of plants are plants in the phylum Filicinophyta. These plants are the ferns. They have a more advanced structure. They have underground stems called rhizomes. They have true roots. They grow large leaves called fronds. Ferns also have specialized cells for transporting water. This is called vascular tissue. Ferns also reproduce both sexually and asexually. Still, they need water to reproduce sexually and so their habitat needs limit their range.

4) Seeds are a major adaptation to life on land. The embryo inside a seed’s protective coat is kept safe from drying out for many years until conditions are suitable for growth. As a result, seed bearing plants are much more widespread and diverse than plants such as mosses and ferns. Seed bearing plants are classified into two main groups – gymnosperms and angiosperms. Gymnosperms bear their seeds exposed on the surface of cone scales or on stalks among their leaves. Plants in the phylum Coniferophyta such as pines, spruce, firs, and cedars are examples. Angiosperms, are the other type of seed bearing plant. These flowering plants develop seeds inside a protective tissue or fruit. They include such species as lilies, roses, tulips, grasses, and every other familiar tree, shrub and plant that produces flowers. In summary, listed below are the major plant Phyla.

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Topic 6 Similarities and Differences Among AnimalsTopic 6 Similarities and Differences Among AnimalsWhat are some of the Major Classifications of Animals?

Phylum Porifera – Sponges these animals are classified as simple because the cells that make them do not form true tissues. See p. 365 for cell structures. Sponges are also said to be simple because they have no systems or organs. Sponges are able to reproduce both sexually and asexually. Phylum Cnidarians –There is more specialization of function in this phylum. There are 2 body types polyps and medusae. Usually polyps anchor themselves with one end of their body. They form colonies in such a manner. The great Barrier reef – one of the largest structures on the planet is made of these things. The other end of polyps contain tentacles that capture prey. Medusae on the other hand are usually free swimming and not anchored like the polyps. Jellyfish are the typical animals in this grouping.

All animals are heterotrophs : they obtain energy for their life processes by consuming other organisms. Each phylum hasis own structures and functions.

Worms Phyla – Platythelminthes, Nematoda, and Annelida –The next grouping of animals includes three phyla of worms. All worms are more complex than sponges or cnidarians. They have specialized groups of cells that work together. Specialized tissues that are grouped together to perform a common function are called an organ. Organs in turn act together in systems to perform major life functions such as responding to stimuli, digestion, obtaining oxygen, circulating blood, and eliminating waste products. The animal is thus stronger and more able to survive by virtue of these adaptations. These systems are called the sensory systems, the digestive system, the respiratory system, the circulatory system, and the excretory system. Lets look at each group of these worms now.Phylum – Platythelminthes the FlatwormsMost of these worms are parasites such as flukes and tapeworms. They live on or in the bodies of various animals including humans.