Cellular and Genetic Mechanisms of Development and Evolution
Mitosis, Meiosis, and Development
Mitosis is crucial for cell proliferation during development post-fertilization.
Meiosis is important before development, as it produces gametes with genetic variation.
Genetic variation from meiosis is essential for natural selection, as it provides a diverse pool of traits that can be selected for or against in a changing environment.
Cell-Cell Recognition in Sea Urchins
Role in Polyspermy: Prevents multiple sperm from fertilizing one egg, ensuring correct chromosome
Read MoreSewage, Fertilizers, and Biomass: Environmental Impact & Treatment
Consequences of Sewage and Nitrate Release
Raw sewage contains organic matter, and together with nitrate fertilisers, increases nitrate and phosphate levels in rivers.
Eutrophication
Eutrophication is the ecosystem response to the addition of such substances to an aquatic system and includes:
- Algal blooms (due to increased nutrients) and a spike in bacteria and microbes feeding on dead algae.
- Increased biochemical oxygen demand (BOD) by saprotrophic bacteria, leading to deoxygenation (reduced dissolved
Human Nervous and Reproductive Systems: Functions and Anatomy
The Nervous System
The nervous system is responsible for perceiving, interpreting, and emitting responses in the face of internal and external stimuli. It has two parts:
- Central Nervous System (CNS): Consists of the brain and spinal cord. It receives information from outside and inside the body, integrates it, and decides the response to be given. It is protected by three protective membranes called meninges: the dura mater, arachnoid, and pia mater.
- Peripheral Nervous System: Formed by motor nerves
Human Physiology: Kidney Function, Menopause, Memory, Aging, Digestion
Kidney Function
Kidneys are localized in the retroperitoneal space, one on each side of the spine at the level of vertebrae T12 to L3. The right kidney is slightly lower due to the right lobe of the liver. Kidneys regulate the internal chemical composition through several processes: filtration, absorption, and secretion. Filtration begins in the glomerulus (podocyte), where a filtrate of plasma is formed. This filtrate passes into Bowman’s capsule through hydrostatic pressure. It then passes through
Read MorePhysiology: Key Concepts in Human Biology
Hypothesis: A prediction or guess about something that is going to happen. Example: How the amount of makeup affects skin clarity. Scientific Method: Observation, ask a question, hypothesis, experiment (dependent and independent variables), data collection, conclusion. Passive Transport: No ATP needed; movement of substances across a concentration gradient (e.g., osmosis). Active Transport: Requires ATP; moves substances from low to high concentration. Hypertonic: Higher concentration of solutes.
Read MoreAutotrophic Nutrition in Cormophyte Plants: Photosynthesis Process
Understanding Autotrophic Nutrition
Autotrophic nutrition in plants is a photosynthetic process where organic matter is formed from inorganic matter, using sunlight as an energy source. Plant nutrition has three phases:
- Alimentation (Feeding): This involves nutrient absorption and transport. Inorganic nutrients (crude sap) are absorbed and transported via the xylem to the cells. Organic substances are created through photosynthesis, and these organic nutrients (elaborated sap) are transported via