Biology Paper 2 Flashcards
What is natural selection?
The process whereby organisms better adapted to their environment tend to survive and produce more offspring.
Key mechanism of evolution proposed by Charles Darwin.
What are peat bogs?
Wetland areas that accumulate peat, characterized by high acidity and low nutrient levels.
Important for carbon storage and biodiversity.
What is the role of hormones in controlling plant growth?
Hormones regulate processes such as growth, flowering, and fruiting in plants.
Examples include auxins, gibberellins, and cytokinins.
What is the purpose of the reaction time practical (RP)?
To investigate factors affecting human reaction time.
Commonly measured using drop tests or light signals.
What is the endocrine system?
A system of glands that release hormones into the bloodstream to regulate bodily functions.
Includes glands such as the pituitary, thyroid, and adrenal glands.
What is the function of the nervous system?
To coordinate the body’s response to internal and external stimuli through nerve impulses.
Composed of the central nervous system (CNS) and peripheral nervous system (PNS).
What is involved in human reproduction?
Processes including gamete production, fertilization, pregnancy, and childbirth.
Includes hormonal control of the menstrual cycle and contractions during labor.
What is genetic inheritance?
The process by which traits and characteristics are passed from parents to offspring through genes.
Governed by principles of Mendelian genetics.
What are genetic disorders?
Diseases caused by abnormalities in genes or chromosomes.
Examples include cystic fibrosis and Down syndrome.
What does the pyramid of biomass represent?
A graphical representation of the total mass of living matter at each trophic level in an ecosystem.
Demonstrates energy transfer and efficiency in food chains.
What is homeostasis?
The maintenance of a stable internal environment in an organism despite external changes.
Includes regulation of temperature, pH, and glucose levels.
What is the function of the kidneys?
To filter blood, remove waste products, and regulate water and electrolyte balance.
Key role in maintaining homeostasis.
What is genetic modification?
The alteration of an organism’s DNA to achieve desired traits.
Techniques include CRISPR and recombinant DNA technology.
What is the RP for Hormones to control plant growth? give the method
Method (Phototropism version – light from one side):
1)Place cress seeds in a Petri dish lined with moist cotton wool or paper towels.
2)Ensure equal spacing between seeds.
3)Place the Petri dish in a dark box with a light source shining from one direction (side light).
4)Leave for several days (e.g., 3–5 days) at room temperature, checking daily.
5)Observe and measure the angle of seedling growth – they should bend towards the light.
6)Compare with a control dish exposed to light from all directions (or kept in total darkness).
What is the RP for Reaction time give the method
Method (Ruler Drop Test):
1)One person (subject) sits with their forearm on a table, hand overhanging.
2)Another person holds a ruler vertically, aligned with the subject’s fingers at the 0 cm mark.
3)Without warning, the ruler is dropped.
4)The subject catches it as quickly as possible.
5)Record the distance (cm) where the ruler was caught.
6)Use a conversion table or equation to calculate reaction time.
7)Repeat 3 times and calculate mean.
Repeat the test after the subject drinks caffeine (or other variable being tested) and compare.
What is an Independant variable?
The one you change!
What is a dependent variable?
The one you measure!
What is a control variable?
The one you keep the same!
What are the control variables for RP Hormones to control plant growth?
Number/type of seeds.
Amount of water.
Temperature.
Type of soil or cotton wool.
Duration of exposure.
Same light intensity (if testing direction only).
What are the control variables for RP
Reaction time
Same person.
Same ruler.
Same starting position of hand.
Same environment (noise, temperature).
No prior practice before testing.
