Cell Structure

Question 1

The main features of plants

Answer 1

They are multicellular
Their cells contain a nucleus with a distinct membrane
Their cells have cell walls made out of cellulose
Their cells contain chloroplasts (so theycan carryout photosynthesis)
Theyfeed byphotosynthesis
Theystore carbohydrates as starchor sucrose
Theydo not have nervous coordination

Question 2

The main features of all Animals

Answer 2

Theyare multicellular
Their cells contain a nucleus with a distinct membrane
Their cells do not have cellulose cell walls
Their cells do not contain chloroplasts (so theyare unable to carryout photosynthesis)
Theyfeed on organic substances made byotherliving things
Theyoften store carbohydrates as glycogen
Theyusuallyhave nervous coordination
Theyare able to move from place to place

Question 3

Define Nuclues

Answer 3

Contains the Genetic Material which controls the activities of cells

Question 4

Define Cytoplasm

Answer 4

A gel like substance which is composed of water and dissolved solutes
Supports the internal Cell Structure
Site of many chemical reactions including the site of Anaeorbic respiration

Question 5

Define Cell Membrane

Answer 5

Holds the cell togehter seperating the inside of the cell from outside
Controls which substances can enter and leave the cell

Question 6

Define Ribosome

Answer 6

Found in the cytoplasm
Site of Protein Synthesis

Question 7

Define Mithochondria

Answer 7

Site of most reactions involved in Aerobic respiration where energy is released to fuel cellular processes
Cells with high rate of metabolsim(carrying out many different cell reactions) Have significantly higher numbers of mithochondrio than cells with fewer reactions.

Question 8

Define Cell wall

Answer 8

Made of cellulose
Gives extra support defining its shape

Question 9

Define Chloroplast

Answer 9

Contains the green chlorophyll pigment (to absorb light energy) and the enzymes needed for photosynthesis

Question 10

Define permenant vacoule

Answer 10

Contains cell sap; A solution of sugars and salts dissolved in water
Used for storage of certain materials
Also helps to support the shape of the plant

Question 11

Describe Bacterial Cells

Answer 11

Theyare microscopic single-celled organisms
Possess a cell wall (made of peptidoglycan, not cellulose),cell membrane,cytoplasm and
ribosomes
Lack a nucleus but contain a circular chromosome of DNA that floats in the cytoplasm
Plasmids are sometimes present - these are smallrings of DNA (also floating in the
cytoplasm) that contain extra genes to those found in the chromosomal DNA
Theylack mitochondria,chloroplasts and other membrane-bound organelles found in
animal and plant cells
Some bacteria also have a flagellum (singular) or several flagella (plural). These are long, thin,
whip-like tails attached to bacteria that allow them to move

Question 12

Define Specialised Cells

Answer 12

Specialised cells are those which have developed certain characteristics in orderto perform
particular functions. These differences are controlled bygenes in the nucleus
Cells specialise byundergoing differentiation:this is a process bywhich cells developthe
structure and characteristics needed to be able to carryout theirfunctions

Question 13

Explain Ciliated Cell and their function

Answer 13

Function: Movement of mucus in the trachea and bronchi
Adaptations:Extensions of cytoplasm at the surface of the cells forms ahri like structures called Cilia which beat to move the mucus and trapped particles upto the throat

Question 14

Explain the function of Nerve Cell and their adaptations

Answer 14

Function:Conduction of impulses
Adaptation: Long so that it can run to and from different parts of the body to the central nervous system.
The cell has extensions and branches, so that it can communicate with other nerve cells, muscles and glands
The Axon (Extension of cytoplasm away from the cell body) is covered with a fatty sheath, which insulates the nerve cell and speeds up the nerve impulses.

Question 15

Explain function of Red Blood Cells and their adaptation

Answer 15

Function: Transport of Oxygen
Biconcave disk shape increases surface area for more efficient diffusion of oxygen
Contains the haemoglobin which joins with oxygen to transport it
Contains no nucleus to increase the amount of space available for for haemoglobin inside cell

Question 16

Explain the function and adaptation of Sperm Cell

Answer 16

Function: Reproduction
Function: The head contains the genetic material for fertilisation in haploid nuclues (Containing half of the normal number of chromosomes)
The Acrosome in the head contains digestive enzymes so that a sperm can penetrate an egg
The Mid-Piece is packed with mithochondrio to release energy needed to swim and fertilise the egg
The Tail enables the sperm to swim

Question 17

Explain the function and adaptation of Egg Cell

Answer 17

Function: Reproduction
Adaptation: Contains a lot of cytoplasm which has nutrients for the growth of the early Embryo
Halpoid Nuclues contains the genetic material for fertilisation
Cell Membrane changes after fertilisation by a single sperm so that no more sperm can enter

Question 18

Explain the function and adaptatio of Rooy Hair Cell

Answer 18

Function: Absorption of water and mineral ions from soil
Adaptation: Root Hair increases surface area of the cell to ensure maximum absorption of water and mineral ions
Walls are thin to ensure water moves through quickly
No chloroplasts present

Question 19

Explain the function and adaptation of Xylem Vessel

Answer 19

Function: Conduction of water through the plant and support of the plant
Adaptation: No top and bottom walls between xylem vessels, so there is a continuos column of eater runnin g througj them
Cells are dead without organelles or cytoplasm to allow free passage opf water
Their walls become thickened with a substance called liginin which means they are able to help support the plant

Question 20

Explain the function and adaptatio of palisade mesophyll cell

Answer 20

Column shaped to maximise the absorption of sunlight and fit as many in a layer under the upper epidermis of the leaf as possible
Contains many chloroplasts for maximum photosynthesis