Biology

Topic A: Science and fiction

9Aa Genetic information

The features of an organism are called its characteristics.
Our characteristics are controlled by genetic information. This information
Organisms can be classified in to different species. A species contains individuals with the same physical characteristics and common ancestors. It’s a group of organisms that can reproduce with each other and produce an offspring that will also be able to reproduce.
Organisms of the same species are similar but not identical.
The differences that occur both between different species and within the same species are called variation.
An animal that is the offspring of parents from two different species is called a hybrid, and it is unable to reproduce.
When genetic information are passed on to an organism from its parents the information are said to be inherited.

Most cells have a nucleus, which is a part of the cell that controls it.
The nucleus contains chromosomes which are huge molecules of DNA found inside the nucleus of the cells.
A chromosome consists of a string of genes.
A gene carries an instruction. It’s the section of a chromosome that controls inherited characteristics of an organism and carries genetic information.
Each gene is a length of DNA. DNA is a long coiled molecule which can unzip and copy itself when a cell divides. It also carries the genetic code and makes up the chromosomes.
Sex cells-egg: In female the sex cells are called eggs. Eggs are produced in sex organs called ovaries.
Sex cells-sperm: In males the sex cells are called sperm. Sperm are produced in sex organs called testes.
Sex cells are also called gametes. They contain half the genetic information for a new organism.
The process of fusing a male gamete with a female gamete is called fertilization and the fertilized egg contains information from the father and the mother. A fertilized egg cell, that will form an offspring, contains information from both the sperm and ovum cell since both are needed.
Children often look similar with their parents because they have inherited some characteristics from the.
Each fertilized egg grows by cell division and grows into an embryo.
Identical twins form if cells in an early embryo split apart.
They have exactly the same characteristics and they are either boys or girls.
If we have twins that are not identical it means that two egg cells are fertilized from two different sperm cells.
Mutation is the change in a gene the often alters the information that the gene carries.

9Aa Focus on: Chromosomes

In all living things, characteristics are passed on in the chromosomes the offspring inherit from their parents.
Each pair of chromosomes contains one chromosome that has been inherited from each parent.
All chromosomes contain many different genes.

Number of pairs of chromosomes: * Human body cells contain 23 pairs of chromosomes (46 chromosomes) * Cat has 19 pairs (38 chromosomes) * Chicken has 39 pairs (78 chromosomes)

Inheritance:
Some characteristics such as eye colour and earlobe shape are only determined by genes. These are called inherited characteristics.
Other types of characteristics, such as scars and hair length, are not inherited but depend on environmental factors. These are called acquired characteristics.

Appearance:
The overall appearance of an organism depends on two things: 1. Its genes (inherited characteristics 2. The effects of the environment in which it lives
All the observable characteristics of an organism are called its phenotype.
The full set of genes of an organism is called its genotype.
An organism’s phenotype depends on its genotype and environmental effects.
Phenotype = genotype + environmental effects
Overall appearance = genes + environment

Allele:
Chromosomes in a pair contain the same type of genes that code for the same characteristic, such as eye colour.
Each chromosome in the pair, however, may have different version of a gene.
Each different version of a gene is called an allele.
Different variation of the same gene is called an allele.
The phenotype for a particular characteristic depends on which allele is dominant and which allele is recessive.
Dominant alleles are always expressed in a cell’s phenotype (Capital letters)
Recessive alleles are only expressed in a cell’s phenotype if two copies of it are present.

Cystic fibrosis:
Sometimes alleles can cause genetic diseases.
Cystic fibrosis (CF) is a genetic disease that damages the lungs and makes digesting food very difficult by producing extra mucus, which is a slimy substance that traps microbes. Mucus builds up in the lungs making breathing difficult and it encourages bacteria to grow causing CF sufferers, lung infections. * To get rid of mucus CF sufferers have physiotherapy sessions.
Cystic fibrosis also affects the pancreas which produces enzymes that help to digest food. The extra mucus blocks the small tube leading from the pancreas to the small intestine and so the enzymes cannot get to the small intestine. * They take tablets containing digestive enzymes.
For a person to have cystic fibrosis they must have CF gene from both parents.
People who have only one CF gene are called carriers. Carriers are perfectly healthy but two carriers may have children with cystic fibrosis. | | Carrier | Carrier | | cf | CF | | cf | cfcf | Cfcf | | CF | CFcf | CFCF |

9Ab Genes and environment

Varieties: plants of the same species with clear differences
Breeds: animals of the same species with clear differences

Shape, color and size are some characteristics that can be seen.
Some characteristics cannot be seen:
Smell
Taste
Resistance to diseases

Natural variation: differences between different organisms of different species/variety/breed caused by genes.

Environmental factors can also cause variation. It is called environmental variation.
There are more differences between organisms of different varieties/ breeds than between organisms of the same breed/variety.

| Natural variation | Environmental variation | Both | Having naturally blue eyes | * | | | Having a scar | | * | | Having naturally curly hair | * | | | Being very tall | | | * | Having a cold | | * | | Being able to speak French | | * | |

Life processes:
Movement
Reproduction
Sensitivity
Growth
Respire
Excretion
Nutrition

Some variations in characteristics are helpful. For example, a rabbit that can run faster than other rabbits is less likely to get caught by a fox. Some variations in characteristics are harmful. For example, if a plant gets a disease that kills its leaves, it will die.

9Ac Different animals

Selective breeding: when humans choose certain plants or animals with useful characteristics and breed more of these organisms. * Breeding sheep to produce more wool * Breeding wheat to produce more grain * Breeding tomatoes to have more flavor * Breeding racing horse to become faster

Genetic modification(manipulation): a process by which the genes of are organism are altered by adding genes from other species.

Cross-breeding: when different varieties or breeds are mated with one another to produce an offspring with characteristics from both breeds and varieties.

Cloning: process by which a part of an organism is used to create an identical organism
A single organism makes a copy of itself with exactly the same genetic code.
It enables an organism to populate quickly a new habitat and ensures that successful characteristics are passed on. * Identical twins are human clones that have exactly the same genes. They are created when a fertilized egg splits in two creating two separate but genetically-identical embryos. * Dolly the sheep: A nucleus from a body cell of an adult is removed and placed into an egg cell that also had its own nucleus removed. The egg cell then acts as a normal fertilized egg, containing though information from only one parent. The DNA could not be taken from a sperm or egg cell because it only contains half information needed.

| Characteristics a farmer would want for each of the animals | Animal | Produces lots of milk | Produces lots of hair | Produces lots of muscle | Produces lots of eggs | Cow | * | | * | | Hen | | | * | * | Sheep | * | * | * | | Pig | | | * | |

9Ad Different plants

GM plants/organisms have had changes into their DNA. * Examples are sweet corn and tomatoes
A lot of people are concern of using GM food

Pollination:
Anthers produce pollen grains which are transferred in plants by wind, humans or insects, to where stigma is. This is called pollination. A pollen tube grows down to the ovary carrying the nucleus of the pollen grain to the ovule to fuse with the egg cell and fertilization occurs.

Cloning in plants
Asexual reproduction: * Reproduction from one parent only * Reproduction that does not involve fertilization
Plant a stem from a plant

Characteristics a breeder would want a flower to have:
Grow tall
Different and nice colors
Resistance to diseases
Smell

Cross-breeding flowers:
The anthers of a flower are cut off.
Pollen grain from the anthers of another flower is brushed onto the stigma.
The flower is placed in a plastic bag so that pollen from other flowers cannot get to it.

Topic B: A model career

9Ba Fighting fit

Fitness is the ability to meet the demands of the environment. Being fit is not necessarily about how fast you can run or how good you are at sport but being able to cope with the demands of your everyday life.
Scientists use criteria to help them decide how fit someone is.
People who are fit have lower resting pulse.

The four S factors: * Strength * Suppleness * Speed * Stamina

Glucose + oxygen carbon dioxide + water
For aerobic respiration, the respiratory and digestive systems are needed.
Heart pumps blood faster during exercise, so more glucose and oxygen is available at muscles, when needed for respiration.
Exercise makes your heart muscles stronger so that it pumps more blood with each beat. People with high stamina have slower resting heartbeat rates. When you get fitter, by increasing your stamina your heartbeat rate also returns to normal more quickly after exercise.

9Bb Easy breathing

The breathing system is used for gas exchange, take in oxygen and get rid of carbon dioxide.
It includes: * Diaphragm and bronchi * Trachea * Lungs
When we breathe in, inhale, the chest/ribs move up and out, the diaphragm is pushed down and so the volume of lungs increases.
When we breathe out, exhale, the chest/ ribs move in and down and the diaphragm goes up, making the volume of lungs smaller.
The flow of air in and out of the lings is called ventilation.
Breathing is the way muscles change the volume of the chest.
Goblet cells in the tubes leading to lungs produce mucus to trap dirt and microbes. The mucus is swept out of the tubes by cilia on ciliated epithelial cells.

9Bb Smoke signals

Smoking cigarettes can cause a stroke or heart attack.
Carbon monoxide reduces the amount of oxygen the red blood cells carry.
Nicotine is an addictive drug that narrows blood vessels, increasing heart rate and also affects the nervous system.
Tar is a brown, sticky substance that forms when tobacco smoke condenses, and destroys cilia and so mucus cannot be removed easily. It can cause lung cancer.

9Bb Striking a balance Diet is the usual food and drink a person consumes and it is very important part of our health. A balanced diet means eating the right amounts of each nutrient so the body gets what it needs.
Nutrients needed and purpose: * Carbohydrates is used as short–term energy * Proteins are used for growth and repair * Fats are used for long-term energy and cell membrane * Water is used as a solvent and for chemical reactions in the body * Vitamins are used for cells to work properly * Minerals make body chemicals * Fibre to keep bowels working properly
A lack of just one of these nutrients can cause a deficiency disease.
Eating too much can also cause a disease since that means that the body consumes more energy than used and that turns to people being overweight for their height, said to be obese.
Obesity is a serious health problem as it affects the heart, blood pressure and can lead to joint problems. Nutrient | Deficiency disease | If eaten too much | Iron | Anaemia | Damage to heart/liver | Calcium | Osteoporosis | Kidneys damage | Protein | Kwashiorkor | | Vitamin A | Night blindnessLiver damage | Tissue damageLoss of coordination | Vitamin C | Scurvy | | Vitamin D | rickets | |

9Bc Drinks and Drugs

Drugs are substances that change the way the body or mind works.
An overdose is when someone takes too much of a drug. This can cause death or serious illness. Other substances may be added to a drug that have unknown effects.
Addiction is the development of a physical or mental need for these substances.
Side-effect is a harmful and unpleasant effect caused by drugs. It can result from an incorrect or impropriate dosage.
Neurons are the basic units of nerve cells that carry and transmit impulses throughout the nervous system.

Stimulants speed up the activity of the nervous system. * Increase alertness * Improve memory and endurance * Raise heart rate and blood pressure * Examples: caffeine, nicotine, cocaine and ecstasy
Depressants slow down the activity of the nervous system. * Cause sleepiness * Reduce anxiety * Can cause pain in high doses(heroin) * Examples: alcohol, heroin

Solvents can make people feel uninhibited, happy and dizzy if inhaled. They can cause heart problems even if taken for the first time.
Breathing in solvents in large amounts is called solvent abuse.

Over-the-counter or prescription drugs:
Medicine: drug that helps the body ease the symptoms of a disease or cure the disease
Antibiotics
Paracetamol
Cough medicine
Recreational drugs:
Alcohol
Tobacco
Nicotine
Caffeine: stimulant
Illegal drugs and side-effects:
Ecstasy: stimulant that causes depression, mental illness or death
Cannabis: causes memory loss
Heroin: dangerous depressant that causes vomiting and severe headaches.
Cocaine: powerful and harmful stimulant. Blocks arteries and causes mental problems.
Topic C: On the farm

9Ca Plant reactions

Plants make their own food through photosynthesis.
The raw materials for this reaction are carbon dioxide from the air and water from the soil.
In this chemical reaction, chlorophyll in plant cells absorbs light energy to change carbon dioxide and water into glucose and the by-product oxygen.
Carbon dioxide + water oxygen + glucose
This equation can be read as:
“Carbon dioxide reacts with water in the presence of chlorophyll and light energy to produce glucose and oxygen.”
Before plants the atmosphere was made up of carbon dioxide and water vapor. Gradually, carbon dioxide was converted into oxygen by photosynthesis and the increased level of oxygen slowly made the planet more suitable for other forms of life.

Respiration is the process that the body uses to release energy from digested food (glucose).
Glucose + oxygen carbon dioxide + water
C6H12O6 + 3O2 6CO2 + 6H2O
This type of respiration is called aerobic because it uses oxygen from the air.

If a factor like the amount of light or a raw material is in short supply, photosynthesis will not happen as fast as it can. The factor is said to be limiting factor.
If one of the reactants starts to run out, photosynthesis will slow down. This is an example of a substance becoming a limiting factor.

Glucose is dissolved in water and carried in phloem vessels. Root cells get glucose from the phloem vessels. They also need oxygen, which they get from the soil. If soil becomes flooded or waterlogged, roots cannot get enough oxygen to respire and so the plant can die.

9Cb Sun, soil and air

Water from the soil enters a plant through tiny root hair cells and passes from one cell to the next across the roots. Xylem vessels in the roots and stem carry water to the leaves, flowers and roots where it evaporates and diffuses out of stomata.

Roots are branched and spread out * to absorb water from a large area of soil and * to anchor the plant in the soil.

Plants need water * For chemical reactions to occur in plant cells * To keep the plant cool * To hold the plant rigid and upright * To provide dissolved minerals that keep the plant healthy * To transport substances around the plant

Health and plant growth
Plants need a small amount of mineral salts for healthy growth
Minerals are dissolved in water in the soil and so plants absorb these nutrients in the water they take in from the soil.
Nitrogen (N): needed for healthy leaves
Phosphorus (P): needed for healthy roots
Potassium (K): needed for healthy flowers and fruit

Inside a leaf

Cuticle: * Layer of wax that coats the layer of a leaf * Prevents water loss by evaporation * Transparent to let light through to the cells below

Vein: * Arranged in tubes * Phloem vessels carry the food (glucose) * Xylem vessels carry water and minerals into the leaf

Stomata: * Tiny holes on the lower part of the leaf that allow gases in and out of the leaf. * Carbon dioxide enters the leaf from the stomata

Guard cell: * Two guard cells surround each stoma in the lower surface of the cell * Change shape to allow opening and closing of the stoma

Epidermis: * The epidermis is a protective layer of cells * Transparent to let light through to the cells below * Leaves have an upper and lower epidermis

Palisade cell: * The palisade cell layer is filled with closely packed cells that contain a lot of chloroplasts. * Most photosynthesis happens here

Spongy mesophyll * Large air spaces between cells * Allows gases to diffuse between the stomata and the palisade cells

9Cc Crop farming

Biomass is any fuel that comes from plants, animals and their wastes
It is the living material that makes up all organisms
Biomass and energy is transferred from one organism to another along food chains
Storage of glucose:
Glucose that is not immediately used by plants is converted into insoluble starch for storage.
Test for starch: if starch is present iodine solution turns into a deep blue color.

Many farmers use intensive farming methods to maximize their yields. In this way * More food is produced in the same space * Cheaper food for consumers * Lower costs for farmers * Increased energy efficiency * Use machinery to get things done quickly

Crops in a yield: * 58% harvested * 13% lost to disease * 13% lost to pests * 16% lost to weeds
Herbicides are used to kill weeds, which would otherwise compete with the crop plants for water, light and mineral salts. Modern herbicides are selective. This means that they kill weeds with broad leaves but do not affect crop plants with narrow leaves.
Pesticides are used to kill pests, such as insects and fungi and so help the farmer to get more produce from the same amount of crop.

Greenhouses can be used to make sure plants have the best conditions for growth
Controlled factors in a greenhouse: * Temperature * Light * Water

Fertilizers contain mineral salts and can be both artificial and natural and help the plants to grow more.
Organic farms only use natural fertilizers.
Decomposers break down animal waste and release mineral salts from it.
New plant varieties may help the farmer to get more produce from the same amount of crop.

9Cd Farming problems

Habitat: has all the things that an organism needs to survive such as: * The right amounts of oxygen * Water * Light * Shelter
Habitat destruction is caused by * Cleaning the land for agriculture (deforestation) * Pollution (inappropriate use of fertilizers, pesticides and herbicides)
Biodiversity is the number and variety of organisms found in an area
Biological control is the reduction of pest populations by natural enemies that include predators. * It can have positive effects killing pests * And negative effects on biodiversity might not target only to kill the intended species
Carbon cycle page 41

Topic D: Crime scene investigation

9Da Forensic botany

Forensic botanist: person who studies plants and his knowledge helps him to suggest what happened in a crime and explain this to a court

Plant lifecycles
Forensic botanists need to know about the lifecycles of many plants.
Typical lifecycle of a flowering plant on page 45:

9Db Forensic entomology

Estimating time of death with forensic entomology:
Smell of a dead body attracts different type of insects
Blowflies are one of the first insects to arrive and lay their eggs on the dead body
The eggs hatch into a small larva and after 200 hours approximately it turns into hard pupa and an adult then hatches out of the pupa.
When the dead body is found the time of death can be estimated by estimating the age of the insects.
Insects on a dead body:

Social behavior of animals is when an organism interacts with other members of its species * Example: * Mother/offspring bond * Waggle dance of a bee

9Dc Animals Detectives

Learned behavior is some kind of behavior that you learned. It is developed through experience which allows us to improve or change our existing responses and develop behavior to new situations. * Example: * A dog learn to “sit” * Mother bears teach their cubs how to hunt * Dolphins know how to swim but trainers at an aquarium can teach them to swim certain ways or to do tricks on command
Learned behavior can be used: * Learning can help humans acquire new skills for survival. * Learned behaviors contribute to the survival of animals * Learned behaviors can also be helpful to people as an important tool or amusement

For example, from early age, babies will react to positive responses from their parents. If a baby displays behavior that its parents respond to, the baby will soon learn to continue the same behavior.

9Dd Forensic psychology

Innate behavior is behavior that people only have little control over them.
Sneezing and removing your hand quickly from a hot object are innate behaviors.
Innate behavior is an automatic, inbuilt behavior that cannot be changed.

Learned behavior is behavior that people and animals get trained to. Most of the time humans decide what to do by using their brain which uses information that is sent from sense organs (eye, ear).

Psychology is the study of human behavior. Forensic psychology is using psychology to answer legal questions. Some forensic psychologists work on murder cases trying to work out the profile of a murdered and his/her motives.
Others help the police in interview suspects to make sure that people are telling the truth.
Some psychologists help criminals to change their behaviors and control their anger.

Stimulus: a change in the environment
Humans respond to both internal and external stimuli.
An external stimulus is a change in the environment around us, for example, the heat of an oven.
An internal stimulus is a change inside the body, for example, the feeling of hunger.

The nervous system can coordinate a response to a stimulus using nerve cells.
Nerve cells or neurons are specialized cells that transmit electrical impulses around the body.

If a stimulus is detected your nervous system sends an impulse along neurons to and from different parts of the body, to coordinate a response. 1. Specific receptors in a sense organ detect a stimulus. 2. An electrical impulse is sent to the brain. 3. The brain processes the information 4. An electrical signal is sent to an effector (muscle or gland) 5. The effector produces a response.