Bio end of year exam

Ecology

Study of how organisms interact with each other and their environment.

Species

A group of organisms that can interbreed and produce fertile offspring.

Population

All the members of one species living in a specific area.

Community

All the populations of different species living and interacting in an area.

Ecosystem

A community of organisms and their physical environment interacting together.

Biome

Large geographic region with a specific climate and characteristic types of plants and animals.

Biodiversity

The variety of life in a particular habitat or ecosystem.

Abiotic factors

Non-living parts of an environment, such as temperature, light, and water.

Biotic factors

Living parts of an environment, such as animals, plants, and bacteria.

Abiotic vs Biotic factors

Abiotic = non-living (e.g., temperature, pH, rainfall); Biotic = living (e.g., predators, plants, decomposers). Both influence population size and interactions.

Tundra

Cold, dry climate; small plants like mosses and lichens.

Coniferous forest

Cold winters, moderate precipitation; evergreen trees like pines.

Deciduous forest

Moderate climate; trees that lose their leaves in winter.

Tropical rainforest

Hot, wet climate year-round; dense, tall vegetation and high biodiversity.

Grassland

Moderate rainfall; grasses dominate, few trees.

Desert

Very dry, extreme temperatures; plants like cacti adapted to store water.

Primary succession diagram

Bare rock → lichens/mosses (pioneer species) → grasses → shrubs → trees → climax forest. Biodiversity increases over time.

Photosynthesis word equation

Carbon dioxide + water → glucose + oxygen (in the presence of light).

Photosynthesis symbol equation

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Carbon dioxide entry

Occurs through the stomata in leaves.

Water absorption

Absorbed by root hairs from soil.

Light absorption

Occurs in chloroplasts, mainly in palisade mesophyll cells.

Upper epidermis

Transparent layer that lets light through.

Palisade mesophyll

Main site of photosynthesis with many chloroplasts.

Spongy mesophyll

Loosely packed cells for gas exchange.

Lower epidermis

Contains stomata for gas exchange.

Guard cells

Open and close stomata to control gas and water exchange.

Effect of light intensity on photosynthesis

Increases rate to a point, then plateaus.

Effect of carbon dioxide on photosynthesis

Increases rate until enzymes are saturated.

Effect of temperature on photosynthesis

Rate increases until optimal temp, then enzymes denature.

Sexual reproduction

Involves two parents and produces genetically varied offspring.

Asexual reproduction

Involves one parent and produces identical offspring.

Advantage of sexual reproduction

Increases genetic variation.

Advantage of asexual reproduction

Faster, no need for a mate.

Mitosis

Produces diploid cells; used for growth and repair.

Meiosis

Produces haploid gametes; used for sexual reproduction.

Function of testes

Produce sperm and testosterone.

Function of ovaries

Produce eggs and hormones like estrogen and progesterone.

FSH

Stimulates egg maturation and estrogen release.

Estrogen

Thickens uterine lining, inhibits FSH, stimulates LH.

LH

Triggers ovulation (egg release).

Progesterone

Maintains uterine lining for pregnancy.

Fertilization

Sperm meets egg forming a zygote.

Pregnancy

Placenta provides nutrients; amniotic sac cushions baby.

Birth

Labor involves contractions and delivery of baby.

Barrier contraception (e.g.

condoms), Prevents sperm from reaching egg; effective and cheap.

Hormonal contraception (e.g.

pill), Prevents ovulation; effective but may have side effects.

Surgical contraception (e.g.

vasectomy), Permanent; very effective but costly.

Gene

A segment of DNA that codes for a protein.

Allele

Different versions of a gene.

Chromosome

A DNA molecule containing many genes.

DNA structure

Double helix made of nucleotides; same code in all organisms = universal code.

Mutation

A change in DNA sequence that can change the protein made.

Natural selection

Organisms with favorable traits survive and reproduce; leads to evolution.

Example of natural selection

Antibiotic resistance in bacteria.

Genetic modification

Changing an organism's DNA to give it new traits.

Example of genetic modification

GM crops with pest resistance.

Telomeres

DNA ends that shorten with each cell division; linked to ageing.

Alzheimer's disease

Progressive brain disorder causing memory loss and confusion.

7 components of a balanced diet

Carbohydrates (energy), proteins (growth), fats (insulation), vitamins (health), minerals (body functions), water (hydration), fiber (digestion).

Monomer

Small unit that joins to form polymers.

Polymer

Large molecule made of monomers.

Macromolecule

Large complex molecules like proteins, carbohydrates, and lipids.

Protein structure

Chains of amino acids folded into shapes; shape determines function.

Kwashiorkor

Caused by protein deficiency; swollen belly.

Marasmus

Caused by lack of calories and protein; severe weight loss.

Enzyme

Biological catalyst that speeds up chemical reactions.

Diagram of enzyme action

Substrate fits into enzyme's active site → reaction → product released.

Factors that denature enzymes

High temperature, extreme pH.

Types of carbohydrates

Glucose (fruit), starch (potatoes), cellulose (fiber in plants).

Triglyceride structure

Glycerol + 3 fatty acids.

Saturated fat

No double bonds; solid at room temp.

Unsaturated fat

Double bonds; liquid at room temp.

Excess carbohydrates

Stored as glycogen or fat.

Excess protein

Broken into urea and excreted.

Excess fat

Stored in adipose tissue.

Cause of coronary heart disease

Buildup of cholesterol in arteries.

Risk factors for heart disease

Poor diet, lack of exercise, smoking, genetics.

Aerobic respiration

Glucose + oxygen → carbon dioxide + water + energy (ATP).

Anaerobic respiration

Glucose → lactic acid + little energy (no oxygen).

Lactic acid graph

During exercise, lactic acid builds up, then drops during recovery.

Homeostasis

Maintenance of a stable internal environment.

Blood glucose regulation

Insulin lowers glucose; glucagon raises it.

Type I diabetes

Caused by lack of insulin; treated with injections.

Type II diabetes

Caused by insulin resistance; managed with diet and exercise.

Diet impact on reproduction

Lack of nutrients affects hormone production and fertility.

GM for food production

Can increase yield, resist pests, and grow in poor soil.

Biodiversity and food web

High biodiversity supports stable, resilient food chains.

Cloning ethics

Concerns over unnatural life, equality, and safety.

Climate change and disease

Warmer temps can increase spread of vector-borne diseases.