S1 – Survival Summary Notes

Plants – What are they good for?

1 – We are investigating what plants need in order to survive. 2 – We are learning how plants take up water.

Plants are all around us and are found in all different shapes and sizes.

It is essential that plants have a supply of water in order to:

Keep their structure

For photosynthesis

To keep cool If plants don’t have water they will shrivel up and die.

Plants take up water from the soil around them by using their roots. This takes up a lot of energy. The tubes that transport water in plants are called xylem. The tubes that transport sugar in plants are called phloem.

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Photosynthesis

3 – We are investigating how plants make and store their energy.

Photosynthesis is the process by which plants use energy from sunlight to produce energy in the form of glucose.

The process of photosynthesis can be written as a word equation as shown below. This makes it easier to see how carbon dioxide and water are used to form glucose and oxygen with the help of light energy and chlorophyll.

How can we prove plants use photosynthesis to make food?

Plants store energy in the form of starch, just like how we store spare energy as fat. Starch can be tested for by iodine.

Iodine is an orange/brown coloured liquid. If starch is present, iodine turns blue/black.

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Products Raw materials

Identifying Organisms – Keys

4 – We are learning to investigate how scientists identify different organisms. 5 – We are learning to use and create a key to identify different organisms and objects.

There are millions of different types of organism in the world and many physical differences that distinguish one from the other. Keys are used to help identify a species. They are based on the physical characteristics of the species to be identified. A key is normally a series of paired statements with simple 'yes / no' answers like in the example below.

Statement Answer

1. Does the animal have four legs? Yes - go the statement 2

No - go to statement 4

2. Does the animal have a curly tail? Yes - pig

No - go to statement 3

3. Does the animal have a hoof divided into two parts? Yes - cow

No - horse

4. Does the animal have webbed feet? Yes - duck

No - human

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Habitats and Distribution –

6 – We are learning the definitions of habitat, population and community. 7 – We are learning to investigate how to quantify the number of species in an area.

Community

All the members of different species that live together in a habitat.

Habitat The place where an organism lives

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Population

All the members of a single species that live in a habitat.

Quadrats are used to estimate the population of a specific area. e.g. If there are 2 daisies per m2 in a field of area 100m2 what is the total estimate of daisies for the full field? We simply multiply the number of daisies per m2 by the area (as long as it is measured in m2 also!). So 2 daisies x 100m2 = 200 daisies

Cells – What are cells?

8 – We are learning about the basic structures of living things

Cells are the basic building blocks of all living organisms. Some organisms, such as bacteria, are made up of only one cell and so are called unicellular. Most living things, such as animals and plants, are made up of millions of cells. Cells are microscopic, so to make them easier to see (i.e. to magnify them) and to enable their structures to be seen more clearly we need to use microscopes.

It is important that we are able to label and identify the different parts of a microscope as shown.

Cells – Plant Cells

9 – We are learning about the structure of plant cells. Using a microscope to look closely at a thin layer of onion or other plant, we should see something similar to that shown. In this image the nucleus and the cell wall are clearly visible. Within the cell wall (surrounding the nucleus) we find cytoplasm.

In other plants, it is possible to see structures such as chloroplasts as shown in this image.

Eyepiece lens

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In order to see all these different structures we add a dye like iodine. This basically stains the different structures making them easier to see.

In the diagram below we can get an idea for the structures that all plant cells are made up of.

Cells – Animal Cells

10 – We are learning about the structure of animal cells. We can easily look at animal cells by rubbing a wet sterile cotton bud on the inside of our cheek for a few seconds and then rubbing the cotton bud on a microscope slide. Adding a dye (e.g. methylene blue) should enable us to see images of skin cells under a microscope like shown below.

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Cell membrane

Cytoplasm

Nucleus

Chloroplast

Cell wall

Vacuole

Cells – Cell Structures

11 – We are learning about cell structures. The diagrams below show the similarities and differences between the structure of animal cells and plant cells. As can be seen, all plant and animal cells have the nucleus, cytoplasm and cell membrane in common, but plant cells also have additional structures like the cell wall, vacuole and chloroplast.

Each part of plant and animal cells has a different job to do. This is necessary for the cell and ultimately the plant or animal to survive. The jobs or functions carried out by each part are listed below.

Structure Function

Nucleus Contains DNA and controls the activity of the cell.

Cell Membrane Controls what goes in and out of a cell.

Cytoplasm The site of chemical reactions.

Cell Wall Provides the cell with a structure and support.

Vacuole Stores water/ cell sap.

Chloroplast Site of photosynthesis.

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Microorganisms – Introduction

12 – We are learning about the different types of microorganisms. Microorganisms are tiny organisms that can only be seen in detail using a microscope. Many microorganisms are unicellular which means they exist as a single cell. There are 3 main types of microorganism:

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Microorganisms are so tiny that we must use very powerful microscopes to see even the largest of them. This image shows bacteria cells on a pin head.

To appreciate the size of microorganisms we can compare them to red blood cells. We can see that the red blood cell itself is very small compared to the width of a human hair. Look at a single hair on your body and then think about the size of the red blood cell.

In the next image you can see the size of the red blood cell (which we just identified as being very small compared to a human hair) in comparison to various bacteria and viruses. These organisms are incredibly tiny even compared to the red blood cell.

Living cells divide to form new cells in order to repair worn-out or damaged tissue throughout an organism. Our cells are constantly going through this process.

Bacterial cells also divide to form new cells. They do this relatively quickly which can lead to large amounts of bacteria developing on our hands etc.

Given conditions that are favourable every 20 minutes bacteria will subdivide:

1⇒ 2 ⇒ 4 ⇒ 8 ⇒ 16 ⇒ 32 ⇒ 64 ⇒

128 ⇒ 256 ⇒ 512 ⇒ 1024 ⇒ 2048

⇒ 4096 ⇒ 8192 ⇒ 16384 Each ⇒ indicates 20 minutes so in just (14 x 20) = 280 minutes or 4.7 hours bacteria can multiply from just one to over 16 000.

Microorganisms – What do they need to live?

13 – We are learning about the conditions microorganisms need to live.

Microorganisms grow in very diverse conditions and as such they are found nearly everywhere on Earth. Although they are good at adapting to their environments, certain conditions promote growth more than others. These conditions include:

Microorganisms thrive in warm and moist conditions but they also need time to be able to multiply and colonize.

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Temperature Moisture Time

Microorganisms – Disease

14 – We are learning about how microorganisms cause disease. Pathogens are microorganisms like viruses and bacteria that cause infectious diseases. These pathogens are around us all the time but we don’t always fall ill because of our bodies defence.

The body’s first line of defence is designed to stop the pathogen entering the body. This includes the skin, chemicals in tears and our stomach acid. This is called Passive Immunity.

The second line of defence uses white blood cells. These white blood cells produce antibodies to destroy pathogens. This is called Active Immunity.

Vaccines Vaccination involves putting a small amount of an inactive form of a pathogen into the human body.

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Microorganisms – Limiting the spread of microorganisms

15 – We are learning ways to limit the spread of microorganisms. You can avoid spreading harmful microorganisms by:

Microorganisms can also be spread in the kitchen through poor hygiene, not cooking food properly and storing food at the wrong temperature. We can avoid this spread by:

Avoiding food that is not fresh or has not been cooked properly.

Keeping uncooked meat

separate from other food in the fridge.

Cooking raw food thoroughly

Washing hands and wiping surfaces clean

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Inheritance – DNA introduction

16 – We are learning about the structure and function of DNA. Inside almost every cell in the human body there are twenty three pairs of chromosomes (46 chromosomes in total). 23 chromosomes come from the male sex cell and 23 from the female sex cell. This means that you inherit 50% of your genetic information from your mum and 50% from your dad.

Along each chromosome are

arranged thousands of genes. These

control all the characteristics of a

person: hair colour, height and even

a tendency to suffer from an illness.

We have two copies of each gene -

one from our mother and one from

our father.

Each chromosome contains one very long

molecule of DNA (deoxyribonucleic acid).

The DNA is arranged in a kind of corkscrew

shape called a double helix. This is made

of two long spirals held together by cross

links a bit like the rungs on a ladder.

These links are made from four types of chemical

building blocks which are arranged in pairs. The order

in which these pairs are arranged carries the

information stored in DNA in the same way that the

letters of the alphabet are arranged to spell out a word.

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Inheritance – DNA Profiling

17 – We are learning about the risks and benefits of DNA profiling.

Each person’s DNA is unique. The sequence of the building blocks in the DNA molecule is slightly different and this is called their DNA profile. Everyone has a unique DNA profile, just like they have a unique fingerprint. DNA profiles are sometimes called genetic fingerprints. DNA profiles or fingerprints can be used in many ways. Just like we can use a person’s fingerprint to identify a criminal, DNA profiling allows a person to be identified from blood, semen, saliva, hair or dead skin left at a crime scene. Crime Scene Scenario A young woman has been assaulted with a knife. DNA evidence has been found on the weapon and three men have had their DNA tested as part of the investigation.

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Some of the DNA markers

from the weapon match to

the victim – confirming that

she was definitely at the

crime scene.

Four of the DNA markers from the weapon

match the DNA of suspect 1, six markers

match suspect 2 and only one matches

suspect 3. This should indicate that suspect

3 was not at the crime scene and suspect 2

is guilty.

Paternity Test Scenario

The Pros of DNA Profiling Less Invasive. Taking a DNA sample is less invasive than taking a blood sample. Reducing and Reversing Wrongful Convictions. When used properly and in conjunction with other forensic tools and evidence, the number of wrongful convictions can be reduced.

Protecting the Innocent. The proper use of DNA profiling can help rule out clear non-matches in paternity cases and crimes in which DNA evidence is present. This can be helpful to those who are wrongly or falsely accused.

The Cons of DNA Profiling Privacy. Some consider any request for a DNA sample to be a violation of an individual’s right to privacy and a violation of their civil liberties. Access to and Use of Data. Some legitimate concerns about DNA collection and profiling involve the access others would have to it and what they would do with it. Health insurers could conceivably use it to deny coverage or claims. Prospective employers could avoid hiring those who have certain genetic traits or risks of certain diseases. Wrongful Convictions. While the appropriate use of DNA can be helpful in reducing and reversing wrongful convictions, inappropriate use of it and the sway of it over other evidence on juries and judges can create a system of wrongful convictions.

Some of the DNA markers

from the child match the

mother as expected.

All the DNA markers of the child that are

not shared with the mother are shared with

Dad 3 which should indicate that he is the

father of the child.