Chapter 2 - Cells

Question 1

what is a cell?

Answer 1

the smallest unit from which all organisms are made

Question 2

what are microscopes and what are they used for?

Answer 2

many biological structures are too small to be seen by the naked eye and so optical microscopes are used by scientists as they allow for tissues , cells and organelles to be seen and studied

Question 3

cell membrane - function

Answer 3

it is a very thin layer of protein and fat that controls what goes in and out of the cell, it is partially permeable and separates the contente of the cell from its environment (surroundings)

Question 4

cell wall - function

Answer 4

tough layer outside the cell membrane ; found in the cells of plants, fungi and bacteria - mainly made of cellulose, if a cell absorbs a lot of water and swells, the cell wall stops its bursting - space between fibres large molecules can go through making is fully permeable

Question 5

what does the cellulose do?

Answer 5

forms fibres which criss-cross over one another to form a very strong covering to the cell which helps to protect and support the cell

Question 6

cytoplasm - function

Answer 6

it’s a clear jelly that’s nearly all water, it contains many substances dissolved in it (especially protein) - metabolic reactions take place here

Question 7

vacuole - function

Answer 7

fluid filled space inside the cell which is surrounded by its own membrane - plant cells have large permanent vacuoles that contain a solution of sugars and other substances called cell sap, animal cells have have smaller vacuoles called vesicles which also contain solutions - when the vacuole is full it presses outward on the rest of the cell and helps it keep its shape

Question 8

nucleus - function

Answer 8

its where genetic information is stored, information is kept on the chromosome which are inherited from the organism’s parents

Question 9

what are chromosomes?

Answer 9

a length of DNA that contains genetic information in the form of many genes, the DNA in them determine the kinds of proteins made in the cell

Question 10

chloroplast - function

Answer 10

found in the cell of plants and contain the green colouring or pigment called chlorophyll

Question 11

what is the function of the chlorophyll?

Answer 11

absorbs energy from sunlight that is used n making food for plants by photosynthesis- contain green starch made by photosynthesis

Question 12

mitochondria - function

Answer 12

found in almost all plant and animal cells - where aerobic respiration takes place releasing energy from glucose for the cell to use, the more energy a cell requires then the more mitochondria it will have

Question 13

ribosome - function

Answer 13

its where the cell makes protein, the instructions on the DNA molecules are used to link together chains of amino acids in particular sequence (where protein synthesis occurs)

Question 14

what structures do bacteria cells have?

Answer 14

they always have cell walls that is not made of cellulose, partially permeable membrane, cytoplasm, ribosome, circle of DNA and plasmid

Question 15

what are tissues?

Answer 15

a group of similar cells that work together to perform a particular function

Question 16

what are organs?

Answer 16

structure made of a group of tissues working together to perform a specific function

Question 17

what is a organ system?

Answer 17

group of organs with related functions working together to perform body functions

Question 18

what is a organism?

Answer 18

living things performing all seven life processes

Question 19

root hair cell - function and adaptation

Answer 19

function:
absorb water and minerals from the soil

adaptation:
<long root hair shape to fit between grains of soil so that it can reach the water
<large surface area for diffusion of water and minerals into the cell
<no chloroplasts due to it being underground

Question 20

what is a specialised cell?

Answer 20

a cell that has developed certain characteristics in order to perform particular functions, the differences are controlled by genes in the nucleus

Question 21

what is differentiation?

Answer 21

the process by which cells develop the structure and characteristics needed to be able to carry out their function

Question 22

palisade cell - function and adaptation

Answer 22

function:
to carry out photosynthesis and make food (glucose) for the plant

adaptation:
>lots of chloroplast to absorb light to provide energy for photosynthesis
>tall, long shape and large surface area to maximise the absorption of light

Question 23

muscle cell - function and adaptation

Answer 23

function:
to help the body move

adaptation:
>contains bands of protein that change shape to contract and relax the muscle
>contains lots of mitochondria to provide energy for muscle contraction

Question 24

nerve cell - function and adaptation

Answer 24

function:
to carry nerve impulses around the body

adaptation:
>long fibres allow it to carry electrical impulses up and down the body
>branching dendrites at each end to connect to other nerves or muscles

Question 25

ciliated epithelial cell - function and adaptation

Answer 25

function:
>to move mucus with trapped dust and microorganisms away from the lungs
>ciliated epithelium is found within the respiratory system (the trachea) and reproductive system of females (fallopian tube of uterus)

adaptation:
>tiny long hairs called cilia to help waft the mucus along the airway
>lots of mitochondria to release energy for cilia to move

Question 26

red blood cell - function and adaptation

Answer 26

function:
to transport oxygen around the body

adaptation:
>biconcave shape increases surface area for the diffusion of oxygen
>no nucleus so that there is more room for haemoglobin which binds to the oxygen molecules

Question 27

white blood cell - function and adaptation

Answer 27

function:
to fight pathogens which cause diseases

adaptation:
>some can change shape to squeeze out of blood vessels and engulf pathogens
>some can produce antibodies and antitoxins

Question 28

sperm cell - function and adaptation

Answer 28

function:
to travel to and fuse with an egg cell for fertilisation

adaptation:
>long tail for movement to the egg
>lots of mitochondria to release energy to allow sperm to move it’s tail

Question 29

egg cell - function and adaptation

Answer 29

function:
to be fertilised by the sperm cell

adaptation:
>cytoplasm contains nutrients for the developing embryo
>the membrane changes after fertilisation to stop any more sperm getting in

Question 30

what equation is used to calculate magnification?

Answer 30

magnification = size of image
size of actual object