Year 8 Biology

A comprehensive set of vocabulary flashcards covering skeletal anatomy, gas exchange, circulatory structures, genetic variation, photosynthesis, microbiology, and cellular respiration.

Skeletal system

The system made up of bones and muscles.

Antagonistic pairs

Muscles that relax and contract at opposite times to move in both directions.

Tendons

Connective tissue that connects muscles to bones.

Ligaments

Connective tissue that connects bones to bones.

Joint

The location where bones meet.

Cartilage

A flexible connective tissue serving as a shock absorber and friction reducer; it makes up the ears and nose and covers the ends of bones.

Bone marrow

Tissue inside the bone that makes blood cells.

Osteoblast

Cells that make and multiply bone cells.

Femur

The thigh bone, which is the largest bone in the human skeleton.

Adult human skeleton

Consists of $206$ bones.

Cranium

The skull, which protects the brain; it is made of fused bones that form a fixed joint and contains $28$ bones.

Ribcage

The structure that protects the lungs, heart, and main blood vessels.

Vertebral column

The backbone, which protects the spinal cord.

Pelvic girdle

The pelvis, which protects female reproductive organs.

Compact bone

The strong part of the bone.

Spongy bone

The part of the bone that keeps it lightweight.

Trachea

The windpipe that moves air into the lungs.

Bronchi

The two tubes into which the trachea splits.

Bronchioles

Many long tubes branching from the bronchi.

Alveoli

Little air sacs at the end of bronchioles where gas exchange occurs; they provide a large surface area.

Diaphragm

A muscle that relaxes and contracts to move air in and out of the lungs by altering the volume of the chest cavity.

Goblet cells

Cells in the trachea that create mucus.

Mucus

A substance that traps dirt.

Cilia

Structures that clear the trachea.

Gas exchange

The movement of $O_2$ and $CO_2$ between the blood and air by diffusion.

Artery

A blood vessel that carries oxygenated blood away from the heart.

Veins

Blood vessels that carry deoxygenated blood to the heart.

Capillaries

Blood vessels that connect arteries and veins; their walls are $1$ cell thick.

Environmental variation

When organisms change because of factors within their environment, such as a tan, scars, and hair length.

Inherited variation

When organisms are different because of their genetics, such as natural hair type and natural eye color.

Continuous variation

Variation that can have any value between points, such as height, weight, and hair length.

Discontinuous variation

Variation that can only have values from a limited number of possibilities, such as blood group or piercings.

DNA

Genetic information found in structures called chromosomes inside the nuclei of cells.

Chromosomes

Structures containing genetic information; human cell nuclei contain $46$ chromosomes, with girls having two $X$ chromosomes and boys having $X$ and $Y$ sex chromosomes.

Genes

Units of inheritance carrying genetic information.

Species

Organisms that are very closely related.

Photosynthesis

The process plants use to make food: $6H_2O + 6CO_2 \rightarrow C_6H_{12}O_6 + 6O_2$.

Chlorophyll

A green pigment in chloroplasts that absorbs light energy from the sun for photosynthesis.

Limiting factor

A variable that slows down the rate of photosynthesis.

Epidermis

The leaf layer that protects the leaf and is transparent to let light energy through.

Guard cell

Cells that control the size of the stoma.

Stomata

Pores through which gases diffuse into and out of the leaf.

Palisade layer

The layer of the leaf that absorbs light energy.

Cuticle

The leaf layer that reduces water loss.

Microorganisms (microbes)

Organisms that can only be seen with a microscope, such as bacteria, viruses, and some fungi.

Pathogens

Microbes that cause disease.

Unicellular

Organisms consisting of only one cell, such as bacteria and yeast.

Multicellular

Organisms consisting of more than one cell.

Viruses

A strand of DNA surrounded by a protein coat; they are smaller than bacteria and fungi and all cause disease.

Budding

A type of asexual reproduction where a daughter cell grows off a parent cell.

Binary fission

A type of asexual reproduction where a cell grows and splits evenly into two identical parts.

Diffusion

The movement of particles from an area of high concentration to an area of low concentration.

Respiration

The release of energy from food inside cells.

Aerobic respiration

Respiration requiring oxygen: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}$.

Anaerobic respiration (Animals)

Respiration without oxygen that produces lactic acid: $C_6H_{12}O_6 \rightarrow 2C_3H_6O_3$.

Fermentation

Another word for anaerobic respiration of yeast, producing ethanol and carbon dioxide: $C_6H_{12}O_6 \rightarrow 2CO_2 + 2C_2H_5OH$.

Energy debt

The result of lactic acid buildup after anaerobic respiration that requires heart and breathing rates to stay high after exercise.

Recovery time

The time it takes for breathing and heart rate to return to normal after exercise.