Unit 2 - Cells and Organelles

Question 1

Name the two main types of organism

Answer 1

Prokaryotes & Eukaryotes

Question 2

Define Organelles

Answer 2

Membrane bound compartment within the cell each providing distinct environments and therefore conditions for different cellular reactions

Question 3

Function of cell-surface membrane

Answer 3

A thin, selectively permeable protein and phospholipid bilayer that controls the movement of materials in and out of the cell, which also has receptor molecules to allow it to respond to chemicals.

Question 4

Function of a plant cell wall

Answer 4

A tough yet elastic wall of cellulose that surrounds and supports the cell wall. It is freely permeable. Defence mechanism against invading pathogens.

Question 5

Function of the nucleus

Answer 5

Comprised of nuclear envelope with nuclear pores, nucleoplasm, nucleolus and DNA molecules . DNA molecules which control the cell’s activities; they associate with histone molecules to form chromatin. Chromatin coils tightly to form chromosomes. The pores in the nuclear envelope allow substances such as RNA to move between the nucleus and cytoplasm. Nucleolus is an area within the nucleus that makes ribosomes.

Question 6

Function of a lysosome

Answer 6

A round organelle surrounded by a membrane, with no clear internal structure that contains digestive enzymes that are kept separate from the cytoplasm by the membrane. these enzymes enable the lysosome to digest invading cells or break down worn out components of the cell..

Question 7

Function of a Ribosome

Answer 7

Small organelle that either floats free in the cytoplasm or is attached to the RER, where proteins are made during protein synthesis.

Question 8

Function of (RER) Rough Endoplasmic Reticulum

Answer 8

A system of membranes enclosing a fluid filled space, the membrane surface is covered with ribosomes, folds and processes proteins made by the ribosomes packaging them into vesicles.

Question 9

Function of (SER) Smooth Endoplasmic Reticulum

Answer 9

A system of membranes enclosing a fluid filled space, synthesises and processes lipids

Question 10

Function of a Vesicle

Answer 10

A small fluid filled sac in the cytoplasm surrounded by a membrane, transports substances in and out of the cell, via the cell surface membrane, and between organelles.

Question 11

Function of Golgi Apparatus

Answer 11

A group of flat fluid filled sacs, sometimes seen with vesicles at the edge. Processes and packages new lipids and proteins, also makes lysosomes.

Question 12

Function of mitochondria

Answer 12

Usually oval-shaped, with a double membrane. The inner membrane is highly folded to form cristae. The fluid inside the cristae is called the matrix. The membrane forming the cristae contains enzymes used in aerobic respiration. Also contain mitochondrial DNA, produce their own enzymes and can reproduce themselves.

Question 13

Function of Chloroplast

Answer 13

Small Flattened structure in plant cells, has a double membrane enclosing a thick fluid called stroma. They also have an internal network of membranes called thylakoid membranes, which form flatten sac called thylakoids. Several thylakoids are stacked to form granum. Grana are linked by thin pieces of thylakoid membrane called lamellae. The grana contain the chlorophyll pigments where the light-dependent reactions occur during photosynthesis.

Question 14

Function of centriole

Answer 14

Component of the cytoskeleton present in most eukaryotic cells. Small hollow cylinders containing microtubules. Two associated centrioles form the centrosome, which is involved in the assembly and organisation of the spindle fibres, and therefore the splitting chromosomes during cell division.
Structure = sets of three microtubules with one in the center.

Question 15

Function of Cilia

Answer 15

Small hair-like structures found on the surface membrane of some animal cells. Cross section appears like a wheel with an outer membrane and nine pairs of microtubules arranged in a ring around two pairs in the center. Microtubules allow the cilia to move which is used to move substances along the cell surface e.g. In the trachea to sweep dust and dirt out of the lungs.

Question 16

Function of Flagella

Answer 16

Long hair-like Structures that stick out from the cell surface and are surrounded by the plasma membrane. Cross section appears like a wheel with an outer membrane and nine pairs of microtubules arranged in a ring around two pairs in the center. Microtubules contract to make flagellum move, this is used to propel cells forward e.g. the tail of a sperm cell, this requires energy.

Question 17

What are similarities between prokaryotic and eukaryotic cells?

Answer 17

They both have a cell membrane, cytoplasm and ribosomes