Everything Flashcards
Photosynthesis
Photosynthesis is the process by which plants, algae, and some bacteria convert light energy, carbon dioxide (CO₂), and water (H₂O) into glucose and oxygen.
Equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Key Factors Affecting Photosynthesis
Light Intensity: Higher light increases the rate of photosynthesis until another factor becomes limiting.
CO₂ Concentration: More CO₂ increases the rate of photosynthesis.
Temperature: Optimal temperatures increase enzyme activity in photosynthesis; too high can denature enzymes.
Limiting Factors in Photosynthesis
Limiting factors control the rate of photosynthesis. The main limiting factors are light intensity, carbon dioxide concentration, and temperature.
Example: In a dim environment, light will be the limiting factor even if CO₂ and temperature are sufficient.
Investigating the Rate of Photosynthesis
Experiment: Measure the rate of photosynthesis by counting oxygen bubbles produced by an aquatic plant like pondweed under different light intensities.
Variables: Independent Variable - Light intensity. Dependent Variable - Rate of oxygen production (bubbles per minute).
The Inverse Square Law
The intensity of light is inversely proportional to the square of the distance from the light source. As the distance from the light source doubles, the light intensity falls to a quarter of its original value.
Xylem and Phloem
Xylem: Transports water and minerals from roots to leaves. Water moves up by transpiration.
Phloem: Transports sugars (food) made in the leaves to other parts of the plant.
Transpiration and Stomata
Transpiration: The evaporation of water from plant leaves, which draws water up through the plant via the xylem.
Stomata: Pores on the leaf surface that open and close to allow gas exchange and water loss by transpiration.
Factors affecting transpiration: Light, temperature, humidity, and wind speed.
Hormones
Hormones are chemical messengers produced by glands, transported in the bloodstream to target organs.
Examples: Adrenaline increases heart rate and blood flow to muscles for a ‘fight or flight’ response. Thyroxine regulates metabolic rate and affects growth.
The Menstrual Cycle
Controlled by hormones including FSH (Follicle-Stimulating Hormone) that stimulates egg development and estrogen production, LH (Luteinizing Hormone) that triggers ovulation (release of an egg), and Estrogen and Progesterone that maintain the uterus lining for pregnancy.
Controlling Fertility
Contraception: Methods to prevent pregnancy, including hormonal methods (e.g., the pill) that regulate the menstrual cycle and prevent ovulation.
Homeostasis
Homeostasis is the regulation of internal conditions (e.g., temperature, blood glucose) to maintain a stable internal environment.
Examples of Homeostasis: Thermoregulation, Osmoregulation, Blood Glucose Control
Controlling Blood Glucose
Insulin lowers blood glucose by promoting the uptake of glucose by cells and its conversion to glycogen in the liver. Glucagon raises blood glucose by stimulating glycogen breakdown in the liver.
Exchange of Materials
Diffusion is the movement of gases and dissolved substances from high to low concentration.
Surface Area to Volume Ratio: Smaller organisms have a larger surface area relative to their volume, enabling efficient diffusion.
The Alveoli
The Alveoli are tiny air sacs in the lungs with thin walls and a large surface area for gas exchange. Oxygen diffuses into the blood; carbon dioxide diffuses out.
The Blood Components
Red Blood Cells carry oxygen using hemoglobin. White Blood Cells fight infections. Platelets help blood clot. Plasma is the liquid part of the blood that transports substances.
The Blood Vessels
Arteries carry blood away from the heart with thick walls to handle high pressure. Veins carry blood to the heart and have valves to prevent backflow. Capillaries are tiny vessels where gas and nutrient exchange occurs.
The Heart Structure
The Heart has four chambers—two
