Biology

Homework- gas exchange

After watching the video clip (under lung structure post) on gas exchange in the lungs, write a detailed account of how gas exchange occurs. You need to include terms such as: surface area, diffusion, alveoli, capillary network etc

You should of course be looking over and making sure that you understand the topics that we have covered (see topic summary post), in order to prepare for the exam. Below is a more detailed summary of the topics, there is obviously much more that you have to look at: Your notes and experiments, this blog and your textbook.

Topics Covered in EAL Biology:

Introduction

? Characteristics of Life (p1-3)

? Scientific method

? Presenting and processing data

Scientific Method

A process or series of logical steps to make sure the experiment is valid, objective, and repeatable

1. Observation/prior knowledge

2. Problem and Hypothesis (an idea that can be tested)

3. Design experiment:

Control group: group that is left alone, under normal conditions, not exposed to independent variable. It is for comparison.

Experimental group: group that is manipulated, changed, exposed to independent variable

Independent variable: the variable that you are changing. There must be only one independent variable that is changed at a time.

Dependent variable: the response to the independent variable. What you are measuring

Controlled variables/constants: environmental conditions that are the same for both groups, to ensure any difference measured is only due to the independent variable

4. Data collection and processing: Collecting the data in a suitable format with units and carrying out any necessary calculations. Presenting the data in a suitable format. E.g. graph, pie chart etc.

5. Conclusion & Evaluation: Was hypothesis supported or refuted? What conclusions can you make from your data? What were the sources of error in your experiment? How could the experiment be improved?

Ecology (p218-231)

? Ecology (Definition of terms, food chains/webs, pyramids of numbers and biomass, predator prey relationship)

? Carbon cycle (photosynthesis and respiration) (p49-55)

? Nitrogen cycle

? Osmosis and diffusion (p20-30)
? Transpiration stream (100-105)

Ecology- is the study of the interaction between living organisms and their environment

Habitat- is where an organism lives

Population- A group of organisms of the same species living together

Community- all of the organisms of all the different species living in the same habitat

Ecosystem- a community and its environment, interacting together

Food chain- a chart showing the flow of energy from one organism to the next

Food web- a network of interconnecting food chains

Producer- an organism that makes its own food. Usually this is via photosynthesis

Decomposer- an organism that gets its energy from dead waste or organic matter

Consumers- an organism that gets its energy by eating other organisms

Herbivore- an organism that gets its energy by eating plants

Carnivore- an organism that gets its energy by eating animals

Trophic level- position of an organism in a food chain or energy level diagram

Pyramid of numbers- numbers of organisms at each trophic level

Pyramid of biomass- the mass of each trophic level

You should also know and understand the following cycles: carbon, nitrogen, and water

You should also know and understand the following:

Factors affecting population size (limiting factors)

Predator prey relationship

The J curve of human population and the differences in age distribution between developing and developed countries

Symbiosis, mutualism, commensalism and parasitism

Symbiosis is where there is a persistent interaction between organisms. There are various forms by which this can take place: where both benefit (Mutualism), where one benefits and the other is not really harmed or helped (commensalism) and where one benefits and the other is harmed (parasitism).

The Carbon Cycle key points:

· The air contains about 0.04% carbon dioxide

· Plants use the carbon atoms in CO2 to make sugars

· When sugars are respired by plants and animals the carbon atoms in the sugar become CO2 again

· Decomposers convert the dead organic matter to CO2 when they break down and respire the material

1. What effect on carbon dioxide levels does cutting down the rain forest have? Explain your answer

2. Why is it important that there is a replantation programme to replace trees that are cut down?

The Nitrogen Cycle Key points:

· The air is made up of about 79% nitrogen (N2)

· N2 is not reactive and plants can?t use it directly

· Nitrogen is changed into a usable form by nitrogen fixation:

Lightning, some nitrogen is converted to oxides and this with water forms nitrates

Nitrogen-fixing bacteria, these live in the root nodules of some plants (beans, clover, peas) and can convert nitrogen into nitrates

· Artificial fertilizers, nitrogen and hydrogen are reacted together to form ammonia (NH3). Ammonium compounds make up fertilisers

· Some plants get their nitrogen source directly from animals e.g. the Venus Fly trap.

· Denitrifying bacteria, these turn the nitrates in the soil back into nitrogen gas

1. Explain why nitrates are a usable form of nitrogen for plants

2. Explain why farmers often add fertilisers to the soil

3. Explain why Carnivorous plants are able to cope with boggy soils which are low in nitrate levels

Cells (p13-30)

? Cells ? Prokaryote and Eukaryote. Plant and Animal (differences and similarities, specialised cells)

? Cell membrane

Cell Organelles Practice

Cell Organelles

See if you can name all the organelles

Movement in a and out of cells (some key terms):

Diffusion: the movement of a substance from a high concentration to a lower one as a result of their random movement.

Osmosis: The diffusion of water molecules from a dilute to a more concentrated solution through a semi-permeable membrane. In effect it is the diffusion of water molecules from a high to a lower concentration. Note that water molecules are small and can pass through the small pores in the partially permeable membrane

The differences between plant and animal cells. Main points:

	Plant Cell	Animal Cell
Differences:	· Bigger · Large vacuole · Have cell wall · Regular cell shape · Have chloroplasts	· Smaller · Small vacuole or not present · No cell wall · Irregular cell shape · No Chloroplasts
Similarities:	· Have nucleus · Have nucleolus · Have mitochondria · Have endoplasmic reticulum · Have ribosomes	· Have nucleus · Have nucleolus · Have mitochondria · Have endoplasmic reticulum · Have ribosomes

Some points about some of the organelles:

Nucleus - Contains the DNA (the genetic information)

Nucleolus ? Produces ribosomes, which move out and are involved with protein synthesis

Vacuole ? In plants these store nutrients and waste products. They also provide turgor pressure, which gives rigidity in plants. In animals, they are involved with intracellular digestion and waste products.

Endoplasmic Reticulum (ER)- There is the smooth, which is involved with production of chemicals such as hormones. The rough ER is involved with protein synthesis as ribosomes are on the surface.

Ribosomes - The messenger RNA moves along them with the transfer RNA bringing the appropriate amino acids to build up particular proteins

Reproduction and Genetics (p165-170) (in plants 182-193) (genetics 194-205) (evolution 206- 214) Genetic engineering 214-217)

? Cell cycle
? Mitosis
? Meiosis

? Genetics (crosses disorders, blood groups, screening, genetic engineering and ethical issues)

? Reproduction in plants (pollination, seed production and dispersal

? Reproduction in humans (IVF treatment)

Reproduction and genetics

Meiosis- including all of the stages, you should be able to recognize and identify the different stages involved. Look at the homework you did where you identified and wrote about the different stages

· Genetic Crosses- You should be able to correctly set out genetic cross diagrams in the way that I showed you, using all of the appropriate terms and labels

· Determination of sex- A simple cross to illustrate this and how the male determines the sex of a child

· Genetic linked disorders- be able to show this with genetic crosses and understand how you have carriers for diseases that are coded for by recessive genes

· Blood Groups- The ABO system. You should be able to show all the possible blood groups and understand that this is coded for by three alleles and A and B show co-dominance

· Sex linked genetic disorders- You need to be able to show a cross for a diseases such as hemophilia, where the male only has one gene and either has the disease or not. You need to understand and be able to explain why this is so

· Understand IVF and genetic screening

The following are some brief definitions of some of the terms. Please also look in your book, where it has the definitions in square boxes.

· DNA- Chromosomes contain long strands of DNA. The DNA contains the codes that instructs which proteins are made

· Gene -length of DNA that codes for a particular protein (characteristic)

· Allele- Two or more forms of a gene

· Meiosis- Reduction division where the chromosome number is halved. Sex cells are made this way

· Haploid nucleus- a nucleus containing a single set of unpaired chromosomes (e.g. sperm and eggs)

· Phenotype- Physical or other features of a gene

· Genotype- Genetic makeup of an organism

· Dominant gene- The allele that is expressed if present

· Recessive gene- An allele that is only expressed if there are two recessive genes present

· Co-dominant- Where neither is completely dominant or recessive, so both influence the phenotype

· Homozygous- Having two identical alleles of a particular gene

· Heterozygous- Having two different alleles of a particular gene

Some key points about mitosis and meiosis.

Mitosis

· Mitosis is where diploid cells produce more diploid cells. This is how all the cells are reproduced, except, the gametes ( sex cells)

· The diploid cells produced by mitosis are the same

· Mitosis is how cells are copied for growth and repair

Meiosis

· Meiosis is how gametes are produced

· It is a reduction division

· The gametes are haploid, they have half the number of chromosomes.

· Meiosis occurs in two stages, meiosis 1 and meiosis 2, in meiosis 1, the homologous chromosomes are separated. This is the reduction division. The second stage is where the chromatids are separated. The result is that the gametes have 23 chromosomes.

A specific area of DNA on a chromosome that codes for a particular characteristic is called a gene. The sex cells will have one set of genes for each characteristic; some will be from the father and some from the father. However, it is chance that determines which particular set of genes are in the sperm or egg and each one will be different. When fertilization occurs, the fertilized egg will have two sets of genes for each characteristic, one from the mother and one from the father. Again it is chance which sperm reaches the egg and manages to fertilise it.

The fertilised egg will have two sets of genes for each characteristic. Which characteristic is actually shown, depends on which gene is dominant over the other. For example, the gene for brown eye colour is dominant over the gene for blue eye colour. Therefore, if the fertilised egg has one gene for blue eye colour and one for brown, the child will have brown eyes. In order for the child to have blue eyes, it must have both the recessive genes for blue eye colour. The dominant gene is represented by a capital letter and the recessive one by a lower case letter.

Genetic Crosses

This shows us the percentage chance of particular characteristics being shown. However, over a small sample these %?s may not be shown at all. An example is shown below:

Mother Father

Phenotype Brown eyes Blue eyes

(characteristics shown)

Genotype B B b b

(the genes present)

production of gametes B b

and fertilisation

B b

You can use the punnet square system:

	b	b
B	Bb	Bb
B	Bb	Bb

Genotype of offspring Bb, Bb, Bb, Bb

Phenotype 100% Heterozygous brown eyes

If the male and female are heterozygous for blue eyes, what eye colour might the offspring ?

Evolution

? Darwin and natural selection

? Importance of evolution now e.g. antibiotic resistance

? Evolutionary timeline

Adaptation and Natural selection

Darwin proposed that all living things were related and that everything evolved from a common ancestor. He realised that there was variation within a population, and that only the best adapted to the environment would survive and pass on their genes (survival of the fittest). This idea of natural selection leading to gradual changes was revolutionary at the time. Sometimes one person can change the way that we think about things and can be correct, even when everyone at the time thinks that they are wrong.

Evidence for evolution

This is a useful link relating to:

? Fossil records

? Similarities of life forms

? Geographical distribution

? Recorded genetic changes in organisms over many generations

Evidence for evolution

The Heart and circulation system (p84-101)

? The structure and function of the heart

? Blood vessels (arteries, veins and capillary network)

? Blood cells (red, white and platelets) Function etc.

? Lung structure and function

http://ealbiologytasis.blogspot.com/2012/05/lung-structure.html

Vital capacity is the maximum amount of air a person can expel from the lungs after a maximum inhalation. It is equal to the inspiratory reserve volume plus the tidal volume plus the expiratory reserve volume.

Expiratory reserve volume: the maximal volume of air that can be exhaled from the end-expiratory position

Tidal volume is the lung volume representing the normal volume of air displaced between normal inspiration and expiration when extra effort is not applied. In a healthy, young adult, TV is approximately 500 ml per inspiration or 7ml/kg body weight

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Biology