Biology Paper 2 Topics Flashcards
What is homeostasis?
Homeostasis is the regulation of the conditions inside your body and cells in order to maintain a stable internal environment
What is the role of receptors in the body?
Receptors detect stimuli ( a change in the environment)
What is the role of coordination centres in the body?
Coordination centres are responsible for receiving information and coordinating a response
What is the role of effectors in the body?
Effectors bring about a change
What three things does the control systems control?
The control systems control body temperatures, blood glucose levels and water content
What are neurones?
Neurones are cells that carry information as electrical impulses
What is the order by which the nervous system undergoes to bring about homeostasis?
Stimulus > Receptor > Sensory Neurone > CNS > Motor Neurone > Effector > Response
What does the CNS consist of?
The CNS consists of the brain and spinal cord
How are the parts of the CNS connected?
The CNS is connected by neurones
What are the two main types of effectors?
The two main types of effectors include:
- Muscles = Contracts
- Glands = Secretes hormones
What does homeostasis maintain?
Homeostasis maintains optimal conditions for enzyme action
What is phototropism?
Phototropism is when shoots of plants grows towards the light
What is auxin?
Auxin is a plant hormone which is used to stimulate growth in plants
Describe the response of a shoot to sunlight
Phototropism
- Shoot is exposed to sunlight
- Auxin accumulates on shaded side
- Cells grow faster on the shaded side
- Shoot bends towards the light
What is gravitropism/geotropism?
Gravitropism/Geotropism is when roots of plants grow towards gravity
Describe the root of the plant during geotropism
Geotropism:
- Auxin accumulates on lower side of root
- Auxin inhibits growth on lower side
- Root bends downwards
What are the commercial uses of auxin?
The commercial uses of auxin include:
- Added to rooting powders to stimulate growth for plant cuttings
- Kills weeds whilst leaving other crops untouched
- Stimulates cell division in tissue culture, promoting cloning of plants
What are the commercial uses of giberellin?
The commercial uses of gibberellin include:
- Promotes seed germination at any time of the year
- Flowering where no specific conditions are needed
- Makes fruits grow larger
What are the commercial uses of ethene?
The commercial uses of ethene include:
- Speeds up fruit ripening
- Effects can be blocked to delay ripening in storage
- Controls cell division
Which receptors detect the change in the body’s core temperature?
Temperature receptors detect the change in the body’s temperature
How does the body respond when the body’s temperature is too high?
When the body’s temperature is too high, blood vessels dilate and blood flows closer to the skin. Sweat glands also produce sweat to transfer out energy
What is Vasodilation?
Vasodilation is when the blood vessels dilate and blood flows closer to the skin in order to transfer heat into the environment
How does the body respond when the body’s temperature is too low?
When the body’s temperature is too low, the blood vessels constrict so less blood flows close to the skin, there is no sweat produced, and the body shivers due to the skeletal muscles contracting
What is Vasoconstriction?
Vasoconstriction is when the blood vessels constrict so less blood flows close to the skin
What is the endocrine system?
The endocrine system is a system made up of glands that secret hormones
What is the role of the pituitary gland?
The pituitary gland, also known as the master gland, stimulates other glands
Which hormone does the thyroid produce?
Thyroid produces thyroxine
Which gland does adrenaline come from?
Adrenaline comes from the adrenal gland
Which gland does insulin come from?
Insulin comes from the pancreas
Which hormone do ovaries produce?
Ovaries produce oestrogen
Which hormone do the testes produce?
Testes produce testosterone
What comparisons can be made between hormones and nerves?
Hormones are slower than nerves but hormones last longer
How many parents are involved in asexual reproduction?
Asexual reproduction involves one parent
Which cell division is involved in asexual reproduction?
Cells in asexual reproduction divide by mitosis
What offspring are produced in asexual reproduction?
Genetically identical offspring is produced in asexual reproduction
What are the advantages of asexual reproduction?
The advantages of asexual reproduction include;
- Faster than sexual reproduction = means many identical offspring can be produced in favourable conditions
- Only one parent is needed = no energy is wasted finding a mate
How many parents are involved in sexual reproduction?
Two parents are involved in sexual reproduction
How do the cells divide in sexual reproduction?
The cells divide by meiosis and mitosis in sexual reproduction
What are the advantages of sexual reproduction?
The advantages of sexual reproduction include:
- Variation increases the chance of individuals surviving a change in the environment
- Selective breeding can be used to increase variation and increase food production
How are gametes formed?
Gametes are formed by meiosis in the reproductive organs
What happens at the end of fertilisation?
At the end of fertilisation, after gametes have fused, the normal number of chromosomes is restored. The fertilised cell will then continue to divide by mitosis to form an embryo.
What is the process of meiosis?
The process of meiosis:
1) . The cell duplicates its genetic information
2) . The cell divides and each new cell has one copy of each chromosome
3) . Both cells divide again to make four gametes
4) . Each gamete has a single set of chromosomes
How many chromosomes do cells contain in meiosis?
In meiosis, the cells contain half the normal number of chromosomes, 23.
What is a population?
A Population is all the organisms of one species living in a habitat
What is a community?
A community is the populations of different species living in a habitat
What is a stable community?
A stable community is a community in which all species and environmental factors are in balance
What is an ecosystem?
An ecosystem is the interaction of a community of organisms and the parts of their environment that are non-living
What is an adaptation?
An adaptation is a feature that enables an organism to survive in the conditions of its normal habitat
What is interdependence?
Interdependence is each species in a community depending upon other species for things eg pollination and seed dispersal
Name examples of biotic factors
Examples of biotic factors include new predators, food availability, competition and new pathogens
Name examples of abiotic factors
Examples of abiotic factors include wind intensity and direction, CO2 levels (for plants), soil pH and mineral content, temperature
What do plants compete for in an ecosystem?
Plants compete for light, space, minerals and water
What do animals compete for in an ecosystem?
Animals compete for food, mates and territory in an ecosystem
What are the three types of adaptation?
The three types of adaptation include structural, behavioural and functional