NSSCO Biology Grade 10-11 Revision Flashcards

A comprehensive set of short question-and-answer flashcards covering core NSSCO Biology Grade 10-11 concepts from the notes.

What is the independent variable in an experiment?

The variable deliberately changed or manipulated by the experimenter.

What is the dependent variable in an experiment?

The variable measured; the observed effect of changing the independent variable.

What is a constant (control) variable?

A variable kept the same throughout the experiment so it does not affect the outcome.

Define a hypothesis.

An educated guess about the relationship between the independent and dependent variables tested in an experiment.

What is diffusion?

Movement of molecules from a region of higher concentration to a region of lower concentration, down a concentration gradient; energy is not required.

Name four factors that influence the rate of diffusion.

Surface area, temperature, concentration gradient, and distance (thickness) of the membrane.

Define osmosis.

Movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane.

Define active transport.

Movement of substances across a membrane against a concentration gradient, requiring energy (usually ATP) and carrier proteins.

Difference between diffusion and active transport.

Diffusion moves substances down a gradient without energy; active transport moves against the gradient using energy.

What is the source of energy for diffusion?

Kinetic energy of molecules; no cellular energy is required.

What are enzymes?

Proteins that act as biological catalysts, speeding up reactions; highly specific for substrates.

Explain the lock-and-key model of enzyme action.

Only substrates that fit the enzyme’s active site will form an enzyme–substrate complex and reactions proceed.

What is the photosynthesis word equation?

Carbon dioxide + water + light energy (and chlorophyll) → glucose + oxygen.

What is the balanced chemical equation for photosynthesis?

6CO2 + 6H2O → C6H12O6 + 6O2.

What is the respiration word equation?

Glucose + oxygen → carbon dioxide + water.

What is the balanced chemical equation for aerobic respiration?

C6H12O6 + 6O2 → 6CO2 + 6H2O.

Name the two main types of cellular respiration.

Aerobic respiration (with oxygen) and anaerobic respiration (without oxygen).

What is a eukaryotic cell?

A cell with a clearly defined nucleus and membrane-bound organelles.

Differentiate plant and animal cells under light microscopy.

Plant cells have a cell wall and chloroplasts and a large central vacuole; animal cells lack cell walls and chloroplasts.

What are xylem and phloem?

Xylem transports water and minerals from roots to shoots; phloem transports sugars (e.g., sucrose) and amino acids in all directions.

Where are stomata located and what is their function?

Stomata are pores on leaf surfaces controlled by guard cells; they regulate gas exchange and water loss (transpiration).

Describe the role of villi in the small intestine.

Villi increase surface area for absorption; they contain a single-layer epithelium, microvilli, a central lacteal for fats, and a capillary network for nutrients.

What is the role of the hepatic portal vein?

Transports nutrient-rich blood from the gut to the liver for processing.

What is the liver’s function in carbohydrate metabolism?

It converts excess glucose to glycogen (glycogenesis) and can convert glycogen back to glucose when needed (glycogenolysis).

What is the function of the kidney in excretion?

Removal of urea and excess water; re-absorption of glucose and some salts.

Define homeostasis.

Maintenance of a constant internal environment, achieved by negative feedback mechanisms.

Differentiate genotype and phenotype.

Genotype is the genetic makeup (alleles present); phenotype is the observable characteristics.

Define haploid and diploid nuclei.

Haploid: a single set of chromosomes (n). Diploid: two sets of chromosomes (2n).

What is mitosis?

Nuclear division producing two genetically identical diploid daughter nuclei; used for growth and tissue repair.

What is meiosis?

Reduction division producing haploid gametes with genetic variation; involves crossing over.

State the concept of natural selection.

Differential survival and reproduction based on heritable variation, leading to advantageous traits becoming more common over generations.

What is translocation in plants?

Movement of sugars (sucrose) and other products through the phloem from sources to sinks.

What is the nitrogen cycle (main processes)?

Nitrogen fixation, ammonification, nitrification, and denitrification.

Describe the structure of DNA.

DNA is a double helix made of nucleotides; bases pair A-T and C-G via hydrogen bonds.

What is the function of bile?

Bile neutralizes stomach acid and emulsifies fats to aid digestion.

Explain the role of enzymes in digestion and how pH/temperature affect them.

Enzymes speed up digestion; each has an optimal pH and temperature; denature outside these ranges.

Define a producer and a consumer in ecosystems.

Producers synthesize organic nutrients (usually via photosynthesis). Consumers obtain energy by eating other organisms.

What is a food chain and a food web?

Food chain shows energy transfer from one organism to another; a food web is a network of interconnected food chains.

What is the function of the stomach’s hydrochloric acid (HCl)?

Kills bacteria and creates acidic conditions for active enzymes like pepsin.

Describe transpiration and factors affecting its rate.

Transpiration is water loss from leaves via stomata; rate is affected by temperature, humidity, wind, and light.

What is the role of the placenta and umbilical cord in pregnancy?

Placenta facilitates exchange of gases, nutrients and wastes between mother and fetus; the umbilical cord contains vessels that connect placenta to the fetus.

Define sexual and asexual reproduction.

Sexual reproduction involves fusion of gametes; asexual reproduction produces genetically identical offspring from a single organism.

What is genetic variation and how is it produced in meiosis?

Variation arises from recombination/crossing over during meiosis, producing genetically different gametes.

What are the four major tissue types in animals and their general roles?

Epithelial, connective, muscular, and nervous tissues; they perform protection, support, movement, and signaling.

Explain the difference between endocrine (hormonal) and nervous control.

Nervous control uses fast electrical impulses for rapid responses; endocrine control uses hormones in the bloodstream for slower, longer-lasting effects.

What is the role of villi and microvilli in absorption?

They dramatically increase surface area for nutrient absorption in the small intestine.

Describe the structure and function of the heart’s chambers and valves.

Two atria receive blood; two ventricles pump blood out; valves (mitral, tricuspid, aortic, pulmonary) prevent backflow.

What is incited by clor tags: osmosis vs diffusion?

Osmosis is diffusion of water across a selectively permeable membrane; diffusion is the movement of solutes from high to low concentration.