Cells

How many chromosomes are in the typical human body cell?

46.

What is the cell formed after fertilisation called?

Zygote.

What is a gene?

A piece of DNA with an instruction of a characteristic.

What are the three stages of meiosis?

1. The starter cell has a full set of chromosomes that copy themselves and stay attached to eachother.

2. The cell splits into two, with each new cell getting half of the chromosomes.

3. Each cell divides into two and splits the chromosomes again; each of the four new cells now have half a set of genetic information.

What is mitosis?

The multiplication and creation of identical cells.

What is meiosis?

The creation of gametes.

How many chromosomes make a full set?

46

How many chromosomes are half a set?

23

What is interphase?

Where the cell makes extra parts.

What are chromosomes?

Lumps of DNA.

What are the 4 stages of prophase?

1. The nucleus breaks down.

2. Chromosomes become visible.

3. Spindle fibres form in the cell.

4. The nuclear membrane starts to disappear.

What happens during metaphase?

Spindle fibres hook onto the chromosomes and start to pull them so they line up in the middle of the cell.

What happens during anaphase?

The chromosomes are pulled apart by the spindles and move to each end of the cell.

What happens during telophase?

The membranes around each chromosome nucleus begins to form and 2 nuclei then grow.

What happens during cytokinesis?

The cytoplasm of the cell separates and the cell membrane divides it into two new cells.

What order does mitosis happen in?

Prophase, metaphase, anaphase, telophase, cytokinesis.

What is growth?

A permanent increase in size or mass.

How are specialised cells made?

Differentiation.

What is a cell that hasn’t differentiated called?

An unspecialised cell or a stem cell.

State a characteristic of red blood cells.

Either: carry oxygen around the body, have a large surface area for oxygen to pass through, no nucleus.

What do muscle cells do?

Stretch and contract to allow movement in the organism.

Where are ciliated cells found?

In the nose and throat.

What do nerve cells do?

They carry electrical impulses around the body.

Why are fat cells stored?

So they can be utilised when the body needs energy.

Why does mitosis need to take place in cells?

To grow, repair and replace.

What are the only places in a plant that do mitosis?

The tips of the roots and shoots.

What is in the central nervous system?

The brain, the spinal cord and the peripheral nervous system.

What are receptor cells and where are they found?

They are in sense organs, and detect changes in the surroundings, also known as a stimulus.

What is the pathway of a nerve impulse?

The stimulus occurs, the impulse starts at the receptor, it’s passed along the sensory neurone, the neurone is relayed in the CNS, it’s passed along the motor neurons, the muscle receives the impulse to react, and the response then occurs.

What do dendrites do?

Receive impulses from receptor cells.

What do axon terminals do?

Pass through to other neurones.