What do scientists call Changes in the environment that we sense, eg light and sound. What do we call cells that detect stimuli?

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1 What do scientists call Changes in the environment that we sense, eg light and sound What do we call cells that detect stimuli? Give examples What is meant by the term Effector. State two examples What is meant by a Reflex? What is the advantage of a reflex? Regulation of an organism s internal environment is known as - State the general pathway of a nervous impulse What two parts make up the Central Nervous System (CNS) Why is homeostasis important for living organisms? In the human body, which conditions require homeostatic control? State the Reflex Pathway What is the Endocrine System? Which provides a faster response, the Nervous system or the endocrine system?

2 Cells that detect are called receptors Receptors in the eye detect light. Receptors in ears detect sound. Receptors in tongue and nose detect chemicals for taste and smell. Receptors in skin detect touch, pain and temperature. Changes in the environment that we sense are called stimuli Reflexes are rapid involuntary actions. The benefit is that they can protect us from danger. An effector brings about a response. Muscles contract. Glands secrete chemicals Stimulus Receptor Co-ordinator (CNS) Effector Homeostasis is the term given to the regulation of the internal environment of an organism Homeostasis is important for maintaining optimal conditions for enzyme action and all cell functions. The Central nervous system (CNS) comprises the Brain and the Spinal cord. Stimulus Receptor sensory neuron relay neuron motor neuron effector response In the human body, homeostasis includes control of Blood glucose concentration, Body temperature and Water levels. The nervous system creates a quicker response than the endocrine system. The effects of hormones are usually slower but longer lasting. The endocrine system is composed of glands that secrete chemicals call hormones directly into the blood stream. The blood carries it to a target organ where it produces an effect.

3 Name the key endocrine glands. What are Hormones? Which gland monitors and controls the glucose concentration in blood? What is the role of the hormone Insulin? What is Glucagon? (Higher) When the pancreas doesn t secrete enough insulin, the person is said to have what disease? How is Type 1 Diabetes treated? If the body stops responding to its own insulin, the person is said to have which disease? How is Type 2 Diabetes treated? What is the role of a negative feedback mechanism? (higher) What is Thyroxin? (higher) Adrenaline hormone is produced in times of fear or stress. What does it do? (Higher)

4 Hormones are chemicals released by glands. They are transported in the blood to the organs that they control (the target organs) Insulin is produced by the pancreas when the blood glucose concentration increases. It causes glucose to be removed from the blood and be stored as glycogen in the liver and muscles. When the pancreas doesn t secret enough insulin the person is said to have Type 1 Diabetes The key endocrine glands are Pituitary (master gland), Thyroid, Pancreas, Adrenal glands, Ovaries and Testes The pancreas monitors and controls blood glucose concentration. It produces the hormone Insulin. Glucagon is a hormone secreted by the pancreas. It is produced when blood glucose concentration is low and causes the liver to break glycogen back down into glucose and release it back into the blood. When the body stops responding to its own insulin, the person is said to have Type 2 Diabetes. Type 1 Diabetes is treated by injecting the hormone Insulin. Negative feedback mechanisms enable the body to maintain a steady state. If a change occurs, negative feedback creates a restoration of the original level. Type 2 Diabetes is usually treated by dietary control (restricted carbohydrate), exercise and medication. Adrenaline causes the heart rate to increase which boosts the delivery of oxygen and glucose to brain and muscles preparing for flight or fight Thyroxin is secreted by the Thyroid gland and stimulates the basal metabolic rate. It is important for growth and development.

5 Name the main male and female reproductive hormones. Name the four hormones involved in the menstrual cycle. Describe the stages of the Menstrual cycle. State two glands which release hormones controlling a woman s menstrual cycle. Describe how hormones can be used as fertility drugs. Describe how hormones can be used as an oral contraceptive Describe the problems with early contraceptive pills and how these were solved with modern versions List some of the methods of contraception available. What is meant by the words Phototropism and Gravitropism (Geotropism)? Describe how plant shoots are sensitive to light and to gravity. Describe how plant roots are sensitive to moisture and gravity What is the name given to the plant hormones that control growth toward light and gravity?

6 The hormones involved with the menstrual cycle are Follicle stimulating hormone (FSH), Luteinising hormone (LH), Oestrogen and Progesterone. The Ovaries release Oestrogen. The Pituitary gland releases FSH and LH Oral contraceptives can contain oestrogen and progesterone. This prevents eggs from being matured in the ovaries. Testosterone is produced in the testes and stimulates sperm production. Oestrogen is produced in the ovaries and is involved with the menstrual cycle. FSH released by the pituitary gland causes an egg to mature in the ovaries and triggers the ovaries to release oestrogen. LH triggers the release of the mature egg. Oestrogen from the ovaries inhibits the further production of FSH.. Progesterone maintains the lining of the uterus and inhibits FSH and LH FSH and LH are used to stimulate eggs to mature in a woman. The eggs are collected and fertilized with sperm from the father. The embryos are inserted into the womans uterus (womb) to develop. Contraceptive methods include Oral contraceptives, Hormonal injections, implants and patches, Barrier methods (condons and diaphragms), Intrauterine devices, Spermicidal agents, Abstinence and Surgical Sterilisation Early contraceptive pills contained high doses of oestrogen and caused side effect. Modern pills contain much lower doses of oestrogen and progesterone only. They have fewer side effects. Plant shoots grow towards light (positive phototropism) and away from gravity (negative gravitropism) Phototropism means growth in response to light (shoots grow toward light). Gravitropism means growth in response to gravity (shoots grow away from gravity). Plant hormones that control growth toward light and gravity are called auxins Plants roots grow toward moisture and gravity (positive gravitropism)

7 Describe how auxins are used in shoots to grow toward light. Describe how auxins are used in roots to grow toward gravity. How are auxins used in horticulture? (Higher) What plant hormone is used to ripen fruit in the food industry. (Higher) How can the plant hormones Gibberellins be used in industry? (Higher) What is meant by the term Asexual reproduction? What is meant by the term Sexual reproduction? What are Gametes? What do we call the process when two gametes join together Why does sexual reproduction lead to variation? How may chromosomes are found in human gametes?

8 In roots, auxins inhibit cell division. There is a higher level of auxin at the bottom side of a root. This side grows slower that the top, so the root grows downwards (toward Gravity) In shoots, auxins trigger cell division. There is a higher level of auxin on the darker side of a shoot, so this side grows faster than the light side. This causes the shoot to grow toward the light. Ethene is used to control fruit ripening. Auxins are used as weed killers, rooting powders and in tissue culture. Gibberellins can be used to increase fruit size (eg grapes), end seed dormancy (brewing) and promote flowering (eg chrysanthemums) In sexual reproduction, male and female gametes join. The offspring show variation because they receive genetic information from two different parents. Asexual reproduction does not involve gametes. It takes place by mitosis. The offspring are clones of the parent Gametes joining together is called fertilisation Gametes are sex cells (sperm and egg in humans, pollen and egg in plants) Gametes (sperm and egg) contain only one set of chromosomes (ie not in pairs) Human gametes have 23 single chromosomes. In sexual reproduction, when the gametes fuse, the offspring has alleles from both parents producing variation.

9 What type of cell division produces Gametes? Describe the stages of Meiosis Which cells divide to form gametes in humans? What is the genome of an organism? What is DNA? What is a gene? What do we find in the nucleus of cells? What molecule is found in the chromosomes and what is the structure of the molecule? Why do plants and animals share similar characteristics as their parents? What is meant by an Allele? What is meant by a Dominant allele? What is meant by a Recessive allele?

10 In meiosis, first the chromosomes are copied. Then the cell divides twice producing four gametes. Each gamete has a single set of chromosomes and is genetically identical. Gametes are produced by Meiosis The genome of an organism is the entire genetic material of that organism In humans, sperm are produced in the testes and eggs are produced in the ovaries. A gene is a small section of DNA on a chromosome. Each gene codes for a particular sequence of amino acids to make a specific protein. DNA is the genetic material in the nucleus which makes up the chromosomes. It is a polymer made up of two strands forming a double helix. Chromosomes are made of the molecule DNA (Deoxyribonucleic acid). DNA has a double helix structure. In the nucleus of cells we find chromosomes which are made of DNA An allele is a form of a gene. Each allele codes for a different protein. The combination of alleles determines the characteristics of an organism. Plants and animals receive genes from their parents which is why they are similar to their parents. A recessive allele can only control a characteristic when there are two copies of that allele (ie there is no dominant allele present) A dominant allele will control a characteristic even when there is only one copy of that allele

11 What is a Homozygote? What is a Heterozygote? What do we mean by the term Genotype? What do we mean by the term Phenotype? What can we use to model a genetic cross to determine the potential offspring What are the sex chromosomes for a female and a male? What is cystic fibrosis and how is it inherited? What is polydactyl and how is it inherited? What do we call the process where an embryo is checked for a defective allele? What concerns surround embryo screening? What do scientists mean by the word Variation? What are organisms of the same species different?

12 A heterozygote is an individual with different alleles for a characteristic (eg, Bb) A homozygote is an individual with two identical alleles for a characteristic (eg, BB, bb) Phenotype describes the physical appearance of an individual regarding a particular characteristic, eg. Blue eyes, Brown hair Genotype describes the alleles present or genetic makeup of an individual regarding a particular characteristic, eg BB, Bb or bb The sex chromosomes are Female = XX Male = XY We can use a Punnett Square diagram to predict the outcome of different genetic crosses. Polydactyl (extra fingers or toes) is a dominant allele. It can be inherited from only one parent. Cystic fibrosis is a disorder of cell membranes. It is a recessive allele, so you can carry the allele without having the disorder. If you are homozygous and have inherited the allele from both parents you will be affected Embryo screening can be used to detect genetic disorders but screening raises economical, social and ethical issues. Checking an embryo for a defective allele is called embryo screening Organisms can have different genetics or have been exposed to different conditions (the environment) or a mixture of both. Variation is the differences in the characteristics of individuals in a population.

13 Describe how evolution by natural selection takes place. What is a mutation and when do they occur? Suggest how a new species might develop. What does the term Selective Breeding mean? Suggest a potential problem caused by selective breeding What is Genetic Engineering? (Higher) How are genes cut and transferred during genetic engineering? (Higher) Explain want is meant by the term GM crop What concerns do some people have about GM crops? What are fossils? State four ways that fossils can be formed State why fossil remains are incomplete.

14 A mutation is a change in the gene that alters the DNA code. They occur during cell division. They may or may not alter the phenotype Organisms within a species show genetic variation. If an organism has an advantageous feature, it is more likely to survive and reproduce. The genes which concur the beneficial feature are then passed onto the next generation. Selective breeding is a process where humans breed plants and animals for desired characteristics (eg milk production, disease resistance) If two populations of a species become so different that they can no longer interbreed to form fertile offspring, they have formed two new species. Genetic engineering is the process where genes are transferred to the cells of plants or animals at an early stage of their development so they develop desired characteristics. Crops that have had their genes modified are known as Genetically modified (GM) crops. GM crops often have disease resistance and higher yields. Selective breeding can result in less variation in individuals which can be detrimental to the species. Genes from the chromosome of an organism are cut out using enzymes and transferred to the new cells by using a vector, usually a bacteria or virus. Fossils are the remains of organisms from many years ago that are found in rocks, ice and other places Some people worry that GM crops might be harmful to wild flowers and insects as well as human health. Fossil remains can be incomplete because Many early forms of life were soft-bodied which leaves few fossils. Fossils can be destroyed eg. By earth movements.. Fossils can be formed 1) From the hard parts of animals that don t decay. 2) From parts of organisms which have not decayed, eg in low temps. 3) Parts of the organism are replaced by other minerals as they decay. 4) Preserved traces eg Footprints.

15 How can extinction be caused? Why are scientists concerned about antibiotic resistant bacteria? What is MRSA? How can we reduce the rate of development of antibiotic resistant strains of bacteria? What was Carl Linnaeus famous for? Why and How has the system of classification altered since Linnaeus? Name the three domains How can evolutionary trees help scientists? What do scientists mean by the term Ecosystem? What is a population? What is a Community A community where all the species and environmental factors are in balance is called a

16 Some mutated strains of bacteria are resistant to antibiotics. They survive and reproduce. This strain will spread as people are not immune and there is no effective treatment. Doctors must prescribe antibiotics appropriately, patients must use the correct antibiotic for the bacterium and patients must complete the prescribed course. Extinction can be caused by New predators, Diseases, Competitors, Catastrophes (eg volcanos), Gradual environmental change MRSA (methicillin-resistant Staphylococcus aureas) is a bacteria which is resistant to antibiotics. Microscopy and Genome mapping has enabled scientists to study organisms at a cellular level. Domains were added above the Kingdom level Carl Linnaeus classified organisms based on their structure and characteristics. Kingdom, Phylum, Class, Order, Family, Genus, Species Evolutionary trees allow scientists to suggest relationships between organisms. The Domains are Archea (eg extremophiles), Bacteria and Eukaryota (protista, fungi, plants and animals) A population is comprised of the same species of organisms An ecosystem is the interaction of a community of living organisms with the non-living (abiotic) parts of their environment. A stable community is where all the species and environmental factors are in balance so that the population sizes remain fairly constant. A community is made up of the different populations. These populations are interdependent within the habitat.

17 List some examples of interdependence within a community Give some examples of Abiotic Factors Give some examples of Biotic Factors What tools do ecologists use to count the number of organisms in a sample area? List some things that animals must compete for Why do adaptations help animals survive? List some of the things that plants must compete for? What do we call an organism which has adaptations that enable them to live in environments unsuitable for most other orgnisms? What kinds of adaptations enable organisms to survive in the conditions which they normally live. Describe how the distribution of organisms can be determined using random sampling with quadrats. Describe how the distribution of organisms can be determined using sampling along a transect. State three ways that organisms can be adapted to deter predators.

18 Abiotic (non-living) factors include Light intensity, nutrients, moisture levels, soil ph, nutrients, wind intensity and direction, CO 2 levels (plants), O 2 levels Interdependence within a community may involve Animals eating plants, Animals pollinating plants, Animals using plant matter for shelter, Plants using droppings for nutrients. Ecologists use quadrats. A sample maybe taken randomly over an area or along a transect. Biotic (living) factors include Availability of food, Predation, Competition, new Pathogens. Animals with adaptations are more successful at competing for resources and are likely to survive and successfully reproduce Animals compete with each other for Food (& Water), Territory and Mates. Extremophiles have adaptations that allow them to live in environments with extreme conditions of salt, temperature or pressure. Plants compete with each other for Light, Space, Water and Mineral ions in the soil Randomly throw quadrat. Count the number of organsims in quadrat. Repeat in a new location. Adaptations maybe Structural (eg shape or colour), Behavioural (eg migration, basking in sun) or Functional (eg antifreeze in cells) Adaptations to deter predators include Thorns, Poisons and Warning colours. Use a tape measure to make a transect. Place quadrat at first point and count number of organisms in the quadrat. Move the quadrat to next point on transect and repeat.

19 What can we say about the surface area of animals living in hot or cold conditions? Describe how plants such as cactus are adapted to living in dry conditions. What do scientists mean by the term Biomass What types of organisms are called Producers in a food chain or web In a food chain, what do we term an organism which eats a producer? List the main stages of the water cycle. How do Decomposers assist in materials cycling? What are detritivores? What is the Carbon Cycle? Which process removes carbon from the atmosphere? Which three process release carbon into the atmosphere? What do scientists mean by the term Biodiversity?

20 Cacti have no leaves to reduce surface area they can lose water from. The stem is used to store water for use in very dry conditions. Cacti have an extensive root system to absorb as much water from the soil as possible. Photosynthetic organisms are the Producers. They are at the start of all food chains as they produce glucose using sunlight. They maybe green plants, algae or phytoplankton Animals living in hot conditions have a large surface area (eg big ears) to increase heat loss. Animals living in cold conditions have a small surface area (eg small ears) to reduce heat loss. Biomass is the mass of living material. The main stages of the water cycle are Condensation, Precipitation, Evaporation, Transpiration and Respiration. Producers are eaten by Primary Consumers. Primary consumers are eaten by Secondary consumers. Detritivores include maggots and some worms and beetles. They start the process of decay and increase the surface area of waste for the decomposers. Decomposers (bacteria and algae) break down waste and dead animals and plants. This returns carbon to the atmosphere as CO2 and mineral ions to the soil. Photosynthesis removes carbon from the atmosphere. The Carbon cycle returns carbon from organisms to the atmosphere as CO 2 to be used by plants in photosynthesis Biodiversity is the variety of all the different species of organisms on earth, or within a particular ecosystem. Respiration, Combustion and Decay all release Carbon to the atmosphere in the form of CO 2

21 Why is it important to maintain a high level of biodiversity? State some of the ways that increased human populations have reduced the amount of land available for other species. How does pollution affect biodiversity? List some land-based sources of pollution caused by human activity. List some of the water-based sources of pollution caused by human activity. How is acid rain produced? How can smoke pollution affect the environment? How might deforestation affect biodiversity? State two negative effects of deforestation. Why is large scale deforestation occurring around the world? State two negative effects of Peat Bog destruction? What types of programme can be used to reduce the negative effects of humans on ecosystems and biodiversity. (Higher)

22 Humans have reduced the amount of land available for other species by building, quarrying, farming and dumping waste High biodiversity helps to ensure the stability of ecosystems by reducing the dependence of one species on another for resources. Pollution can occur on land from landfill, industrial and household waste of toxic chemicals. Pesticides and herbicides from agriculture. Pollution can kill plants and animals resulting in a lower level of biodiversity. Sulfur dioxide and Nitrogen oxide from combustion dissolve in rainwater to produce dilute sulfuric and nitric acid acid rain Water-based pollutants come from untreated sewage, toxic chemicals and chemical run-off from landfill sites, pesticides and herbicides. Deforestion destroys habitats which reduces biodiversity. Deforestation is happening to clear land to grow food staples, to rear more cattle for the beef market, to grow crops for biofuel (ethanol) Smoke pollution is an increase in particulates in the air. These reflect sunlight which causes a dimming at earth. This might produce cooler temperatures at the earth surface. Burning and decay by microorganisms increases the release of CO 2 into the atmosphere. Removing trees reduces the Carbon Sink Programmes to help maintain biodiversity include Breeding programmes for endangered species. Protection and regeneration of rare habitats, Reintroduction of hedgerows, Reduction in deforestations and CO2 emissions, Recycling resources. Removing peat from peat bogs results in a loss of habitat and biodiversity. Peat is a carbon store. This carbon is released to the atmosphere when peat is burned.

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