Results for "0610"

How are new cells produced?

By division of existing cells.

What is the function of ciliated cells?

Movement of mucus in the trachea and bronchi.

Why are root hair cells specialized?

For absorption of water and mineral ions.

What is the role of palisade mesophyll cells?

Photosynthesis.

What do neurones do?

Conduct electrical impulses.

Why are red blood cells important?

Transport oxygen.

What is the purpose of sperm and egg cells (gametes)?

Reproduction.

What is the formula for magnification?

Magnification = image size ÷ actual size.

What provides energy for diffusion?

The kinetic energy of random movement of molecules and ions.

How do substances move into/out of cells?

By diffusion through the cell membrane.

How does water move across membranes?

Via osmosis through partially permeable membranes.

How does osmosis support plant structure?

Water pressure inside cells presses outward on cell walls, providing support.

What role do protein carriers play in active transport?

They move molecules or ions across a membrane.

What are starch, glycogen, and cellulose made from?

Glucose.

What are proteins made from?

Amino acids.

What are fats and oils made from?

Fatty acids and glycerol.

What is a catalyst?

A substance that increases the rate of a chemical reaction without being changed.

Where is chlorophyll found?

In chloroplasts.

What does chlorophyll do?

Transfers energy from light into chemical energy for carbohydrate synthesis.

Write the balanced equation for photosynthesis.

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Why are nitrate ions important for plants?

For making amino acids.

Why do plants need magnesium ions?

For making chlorophyll.

How are leaves adapted for photosynthesis?

Large surface area and thin structure maximize light absorption and gas exchange.

What causes scurvy?

Lack of vitamin C.

What causes rickets?

Lack of vitamin D or calcium.

What is physical digestion?

Breaking food into smaller pieces to increase surface area for enzymes.

What is the role of chemical digestion?

Break down food into small, soluble molecules for absorption.

Where are amylase, protease, and lipase secreted?

Amylase: mouth/pancreas;
Protease: stomach/pancreas;
Lipase: pancreas.

Where are nutrients absorbed?

In the small intestine.

Where is most water absorbed?

Small intestine, with some in the colon.

What does xylem transport?

Water and mineral ions.

What does phloem transport?

Sucrose and amino acids.

How do root hairs aid water uptake?

Large surface area increases absorption efficiency.

How does water exit leaves?

Evaporates from mesophyll cells, diffuses out through stomata as vapor.

What do arteries do?

Carry blood away from the heart.

What do veins do?

Return blood to the heart.

What is the role of capillaries?

Exchange of substances (e.g., oxygen, nutrients) between blood and tissues.

What do red blood cells do?

Transport oxygen via hemoglobin.

What do white blood cells do?

Phagocytosis and antibody production.

What do platelets do?

Aid in blood clotting.

What is plasma’s role?

Transports blood cells, ions, nutrients, urea, hormones, and carbon dioxide.

Why is blood clotting important?

Prevents blood loss and pathogen entry.

How are pathogens transmitted?

Direct contact (e.g., blood) or indirect contact (e.g., surfaces, food, air).

What are antigens?

Unique molecules (e.g., proteins) on pathogens.

How do antibodies work?

Complementary shapes bind to specific antigens.

What is active immunity?

Gained after infection or vaccination, involving memory cells.

Why is passive immunity temporary?

No memory cells are produced.

What causes cholera symptoms?

Toxin-induced chloride ion secretion leads to osmotic water loss (diarrhea).

What is the word equation for aerobic respiration?

Glucose + oxygen → carbon dioxide + water.

Write the balanced equation for aerobic respiration.

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Why is anaerobic respiration less efficient?

Releases much less energy per glucose molecule than aerobic respiration.

What is the word equation for anaerobic respiration in yeast?

Glucose → alcohol + carbon dioxide.

What is the word equation for anaerobic respiration in muscles?

Glucose → lactic acid.

What causes muscle fatigue during exercise?

Lactic acid buildup and oxygen debt.

How is carbon dioxide excreted?

Through the lungs.

What do kidneys excrete?

Urea, excess water, and ions.

Where is urea formed?

In the liver from excess amino acids.

How do electrical impulses travel?

Along neurones.

What do synapses ensure?

Impulses travel in one direction only.

What does glucagon do?

Secreted by the pancreas to increase blood glucose.

What does insulin do?

Decreases blood glucose concentration.

Why are bacteria useful in biotechnology?

Rapid reproduction and ability to make complex molecules.

Why are antibiotics less effective against some bacteria?

Bacterial resistance (e.g., antibiotic-resistant strains).

Do antibiotics affect viruses?

No; they only target bacteria.

What is a haploid cell?

Gametes (e.g., sperm/egg) with half the chromosome number.

What is a diploid cell?

Zygotes with full chromosome pairs (e.g., 23 pairs in humans).

What is fertilization?

Fusion of a pollen nucleus with an ovule nucleus.

What happens during early embryo development?

Zygote forms a ball of cells that implants into the uterus lining.

How can pathogens affect a fetus?

Toxins/pathogens cross the placenta.

What is HIV/AIDS?

HIV is a pathogen causing an STI; AIDS is its advanced stage.

What are chromosomes made of?

DNA, containing genes.

How do genes determine proteins?

The sequence of bases in a gene dictates the amino acid sequence.

What is mitosis used for?

Growth, tissue repair, cell replacement, and asexual reproduction.

What happens before mitosis?

Exact replication of chromosomes.

What is meiosis involved in?

Production of gametes.

What defines a pure-breeding organism?

Homozygous for a trait (e.g., identical alleles).

What is discontinuous variation?

Limited phenotypes with no intermediates (e.g., blood groups).

What causes continuous variation?

Combined effects of genes and the environment.

How are new alleles formed?

Through mutations.

What increases mutation rates?

Ionising radiation and certain chemicals.

What are sources of genetic variation?

Mutation, meiosis, random mating, and fertilisation.

What is the primary energy source for ecosystems?

The Sun.

What are consumers classified as?

Primary, secondary, tertiary, or quaternary based on food chain position.

How do microorganisms contribute to the nitrogen cycle?

Decomposition, nitrification, nitrogen fixation, and denitrification.

What factors affect population growth?

Food supply, competition, predation, and disease.

How do humans negatively impact habitats?

Altering food webs/chains (e.g., deforestation, pollution).

What resources can be sustainably managed?

Forests and fish stocks.