Edexcel GCSE Biology Paper 1 Flashcards

Flashcards covering topics 1-5 of Edexcel GCSE Biology Paper 1, including cells, control, genetics, natural selection, genetic modification, health, disease, and medicines.

What is magnification?

Image size divided by object size.

What is the function of the cell membrane?

It keeps everything in the cell and is semi-permeable, allowing certain substances to pass through.

What is the function of mitochondria?

Respiration takes place there, releasing energy for the cell to function.

What is the function of ribosomes?

Proteins are assembled or synthesized there.

What is the role of enzymes?

Biological catalysts that break down larger molecules into smaller ones.

What is the lock and key principle in enzymes?

The substrate binds to the enzyme's active site only if it is the right shape.

How does temperature affect enzyme activity?

It increases the rate of enzyme activity up to the optimum temperature, after which the enzyme denatures.

How does pH affect enzyme activity?

Similar to temperature, enzymes have an optimum pH, and high or low pH can cause denaturation.

What is diffusion?

Movement of molecules from an area of high concentration to an area of low concentration.

What is osmosis?

Diffusion of water across a semi-permeable membrane.

What is active transport?

Movement of substances through a membrane using carrier proteins and energy, against a concentration gradient.

What is the difference between diploid and haploid cells?

Diploid cells have pairs of chromosomes (23 pairs in humans), while haploid cells have half the number (23 in human gametes).

What is the purpose of mitosis?

To duplicate new cells for growth and repair, resulting in two identical cells.

What are stem cells?

Cells that haven't yet specialized.

What are the components of the central nervous system (CNS)?

The brain and spinal cord.

What is the role of neurotransmitters in the nervous system?

Chemicals that transmit a signal across the synapse between neurons.

What is a reflex arc?

A pathway where a signal bypasses the brain and goes straight through the spine to the effector, resulting in a faster, involuntary response.

What are the three parts of the brain and their functions?

Cerebral cortex (higher-level functions), cerebellum (motor skills), and medulla oblongata (unconscious actions).

What is accommodation in the eye?

The eye's ability to change the shape of the lens to focus light from objects at different distances.

How does the lens change shape to focus on distant objects?

Ciliary muscles relax, suspensory ligaments tighten, and the lens becomes thin.

How does the lens change shape to focus on near objects?

Ciliary muscles contract, suspensory ligaments slacken, and the lens becomes fatter or thicker.

What is myopia?

Short-sightedness, difficulty focusing on far objects.

What is hyperopia?

Long-sightedness, difficulty focusing on near objects.

What is the purpose of meiosis?

To make gametes for sexual reproduction.

What is the difference between sexual and asexual reproduction?

Sexual reproduction involves gametes and results in variation. Asexual reproduction doesn't involve gametes and results in genetically identical offspring.

What is a genome?

All the genetic material in an organism.

What is a gene?

A section of DNA that codes for a specific protein.

What is the difference between genotype and phenotype?

Genotype is the genetic code, while phenotype is how that code is expressed in characteristics.

What is an allele?

Different types of the same gene.

What is the difference between dominant and recessive alleles?

Dominant alleles express a characteristic even if another allele is present, while recessive alleles are only expressed when there is no dominant allele.

What are homozygous and heterozygous alleles?

Homozygous alleles have only one type of allele (e.g., BB or bb), while heterozygous alleles have two different alleles (e.g., Bb).

What is the role of selective breeding?

To breed living things with desired characteristics to enhance these.

What is genetic modification?

The process of altering the genes of an organism.

What are fossils?

The remains of organisms that died a long time ago.

What is the difference between communicable and non-communicable diseases?

Communicable diseases are caused by pathogens, while non-communicable diseases are not.

What is a carcinogen?

Anything that increases the risk of cancer.

What is BMI?

Body Mass Index, an indication of whether or not somebody has a healthy weight or not relative to their height.

What are pathogens?

Viruses, bacteria, fungi, or protists that cause communicable diseases.

How do bacteria harm the body?

Release toxins that damage the body's cells.

How does the body protect itself from pathogens?

Skin, mucus, digestive acids, and white blood cells.

What is the function of lymphocytes?

Produce antitoxins to neutralize poisons and antibodies that stick to antigens on pathogens to stop infection.

How do vaccines work?

Expose the immune system to a dead or inert version of a pathogen so it can produce antibodies without causing infection.

What do antibiotics do?

Kill bacteria but not viruses.

How are drugs trialed?

Lab trials, animal trials, and human trials with placebo control groups.