Edexcel Biology GCSE Topic 2: Cells and Control

Flashcards based on key concepts from Edexcel Biology GCSE Topic 2: Cells and Control, covering important definitions and processes.

What is the role of chromosomes in the nucleus?

Chromosomes contain coils of DNA that carry genetic information.

How many pairs of chromosomes are present in human body cells?

There are 23 pairs of chromosomes in each human body cell, totaling 46 chromosomes.

What are gametes and how many chromosomes do they have?

Gametes are sex cells that contain half the number of chromosomes, resulting in 23 chromosomes.

What is the difference between diploid and haploid numbers of chromosomes?

Diploid number is the total number in body cells (46 in humans), while haploid number is half this amount found in gametes (23 in humans).

What are the three stages of the cell cycle?

Stage 1 is Interphase (cell grows and DNA is replicated), Stage 2 is Mitosis (chromosomes line up and are pulled apart), Stage 3 is Cytokinesis (the cell divides).

What are the main purposes of mitosis?

Mitosis is important for growth, development, and replacing damaged cells.

What type of reproduction does mitosis relate to?

Mitosis is vital for asexual reproduction, where offspring are produced from a single organism.

What happens during cell differentiation?

After mitosis, cells can differentiate into specialized forms adapted to their functions.

What is the role of auxins in plant growth?

Auxins control the elongation of plant cells, allowing them to grow longer in specific directions.

What defines cancer at the cellular level?

Cancer is caused by uncontrolled cell division leading to the formation of tumors.

How do we use percentiles to monitor growth?

Percentiles indicate the relative weight/length of an organism compared to a population, helping assess normal growth rates.

What are embryonic stem cells and their potential uses?

Embryonic stem cells can differentiate into any type of cell and may be used to replace damaged cells in conditions like diabetes or Alzheimer's.

What is therapeutic cloning?

Therapeutic cloning produces an embryo with the same genes as a patient to harvest stem cells for tissue or organ growth.

What is the main function of the brain in the nervous system?

The brain controls consciousness, movements, thoughts, and emotions as part of the CNS.

What are the roles of the cerebral hemispheres and cerebellum?

Cerebral hemispheres manage higher cognitive functions, while the cerebellum controls fine motor activities.

What is a reflex arc?

A reflex arc is the pathway taken by nerve impulses during an automatic response to stimuli, allowing quick reactions.

What structures help the eye focus on objects?

Ciliary muscles and suspensory ligaments control the shape of the lens for focusing on objects at various distances.

What happens to the lens during accommodation for near and distant objects?

For near objects, ciliary muscles contract and the lens becomes thicker; for distant objects, the muscles relax and the lens becomes thinner.

What is myopia and how can it be corrected?

Myopia is short-sightedness caused by a lens that is too curved; it can be corrected with concave lenses.

What is hyperopia and how can it be corrected?

Hyperopia is long-sightedness due to a lens that is too flat; it can be corrected with convex lenses.

What are cataracts?

Cataracts are the clouding of the lens of the eye, which can restrict vision and may require surgical lens replacement.

What genetic condition often leads to colour blindness?

Colour blindness often arises from a lack of specific cone cells in the retina, and is typically a genetic condition.