Key Biological Concepts

Question 1

What two things can organisms be?

Answer 1

Eukaryotes or Prokaryotes

Question 2

What are Eukaryotic cells?

Answer 2

Cells that have a true nucleus. The chromosomes are linear rather than circular.

Question 3

What are Prokaryotic cells?

Answer 3

Cells that do not have a membrane-bound nucleus and their DNA is free in the cytoplasm.

Question 4

What are Eukaryotes?

Answer 4

Organisms made up of eukaryotic cells.
Animals, plants and fungi are eukaryotes. They have a membrane-bound nucleus and their chromosomes are linear rather than circular

Question 5

What are Prokaryotes?

Answer 5

A prokaryote cell. (A single celled organism).
Bacteria are prokaryotes. They do not have a membrane-bound nucleus and their DNA is free in the cytoplasm.
Bacteria have a single circular chromosome in the centre of the cell that holds all the genes needed for that bacterium. Bacteria also have extra circles of DNA called plasmids.

Question 6

What do Bacterial cells not have?

Answer 6

They do not have a nucleus.

Question 7

What is a nucleus?

Answer 7

Contains DNA and genetic material that controls the activities of the cell.
(Genetic material is arranged into chromosomes).

Question 8

What is a cytoplasm?

Answer 8

A gel-like substance where most of the chemical reactions happen.
+ Contains enzymes - controls the chemical reactions.

Question 9

What is a cell membrane?

Answer 9

It holds the cell together and controls what goes in and out.

Question 10

What is mitochondria?

Answer 10

Where most reactions for respiration take place.

Question 11

What are ribosomes?

Answer 11

These are involved in translation of genetic material in synthesis of proteins.

Question 12

What is a cell wall?

Answer 12

A rigid wall made of cellulose. Supports the cell and strengthens it.

Question 13

What is a vacuole?

Answer 13

It maintains the internal pressure to support the cell.

Contains cell sap (weak solution of sugar and salts.)

Question 14

What are chloroplasts?

Answer 14

Where photosynthesis occurs.
+ Makes food for the plant.
+ Contains a green substance - chlorophyll.

Question 15

What are the functions of an egg cell?

Answer 15

+ Contains nutrients in cytoplasm to feed embryo.
+ After fertilisation, membrane changes structure - stops more sperm getting in - makes sure offspring ends up with right amount of DNA.
+ Has a haploid nucleus.

Question 16

What are the functions of a sperm cell?

Answer 16

+ Has long tail to swim to egg
+ Contains lots of mitochondria (in middle section) - provides energy [from respiration] to swim.
+ Contains an acrosome (at the front of the “head”) - stores enzymes required to digest through egg cell membrane.
+ Has a haploid nucleus.