CB1- Key Concepts In Biology

Question 1

Total magnification

Answer 1

Total magnification= eye piece lens x objective lens

Question 2

Magnification

Answer 2

Magnification= image size / actual size

Question 3

What is a eukaryotic cell?

Answer 3

• a complex cell which contains genetic material within an enclosed nucleus
• examples of this include plants and animals

Question 4

What is a prokaryotic cell?

Answer 4

• prokaryotic cells are smaller and simpler and do not have all their genetic material enclosed in a nucleus
• many of them do not have nucleus’
• an example of this is bacteria cells

Question 5

What is the function of a nucleus?

Answer 5

• A nucleus contains all the genetic material for a cell (DNA)
• this is arranged into chromosomes

Question 6

What is the function of cytoplasm?

Answer 6

• a gel like substance where all the chemical reactions occur
• also contains enzymes to control these chemical reactions

Question 7

What is the function of cell membrane?

Answer 7

• controls what enters and leaves the cell
• also maintains the structure of the cell

Question 8

What is the function of mitochondria?

Answer 8

• where cell aerobic respiration occurs, respiration transfers energy that the cell needs to work

Question 9

What are the functions of ribosomes?

Answer 9

• ribosomes create new proteins
• they are also involved in the translation of genetic material in the synthesis of proteins

Question 10

What is the function of cell walls?

Answer 10

• cell walls are made of cellulose and it supports the structure of the cell

Question 11

What is the function of a vacuole?

Answer 11

• a vacuole contains cell sap and maintains the internal pressure to support the structure of a cell

Question 12

What is the function of chloroplasts?

Answer 12

• chloroplasts contain chlorophyll which absorbs and traps energy from sunlight and is where photosynthesis takes place

Question 13

What three additional sub-cellular structures do plants have that animals do not?

Answer 13

• cell walls
• vacuole
• chloroplast

Question 14

What is flagellum?

Answer 14

• a long hair like structure that rotates to make the bacterium move
• it can move the bacteria away from threats like toxins and towards things like nutrients and oxygen

Question 15

What is plasmid DNA?

Answer 15

• small loops of extra DNA that are not apart of the chromosomal DNA
• plasmid DNA contains the genes for things such as drug resistance

Question 16

What is chromosomal DNA?

Answer 16

• one long circular chromosome that controls the cells activities and replication
• this is not contained inside a nucleus and it rather flows freely throughout the cytoplasm

Question 17

What are bacterial cells walls?

Answer 17

• the cell walls on bacterium are different to the cell walls on plants because rather than being made up of cellulose, it is made up of peptidoglycon

Question 18

What are specialised cells?

Answer 18

• cells which have a specific function and have structures that make then specially adapted to complete this function

Question 19

Explain the function of egg cells and how they are adapted to their functions?

Answer 19

• during sexual reproduction, the nucleus of egg cells (gamete’s) fuse with the nucleus of sperm cells to create a fertilised zygote that will develop into an embryo
• egg cells will carry the female dna and support the embryo in its early phases
• straight after fertilisation, the cell membrane will change structure, becoming hard, to stop anymore sperm from entering
• the cytoplasm also contains many nutrients to supply the fertilised egg cell with energy and raw materials for growth and development
• it also has a jelly coat which protects the egg cell, this will also harden after fertilisation so that additional sperm do not enter the egg
• it contains a haploid nucleus, with only 23 chromosomes, this way, once fusing with the sperm cells it will have the correct amount of 46 chromosomes

Question 20

Explain the function of sperm cells and their adaptations

Answer 20

• during sexual reproduction, the nucleus of egg cells (gamete’s) fuse with the nucleus of sperm cells to create a fertilised zygote that will develop into an embryo
• sperm cells transport the males DNA to the female egg cell
• these cells have long tails designed for efficient swimming to the egg cell
• have lots of mitochondria in the middle section to provide energy from respiration
• there is an acrosome at the front of the head, that contains digestive enzymes that can break their way through the membrane of an egg cell
• streamlined shape at the head allowing for more efficient swimming
• also contains a haploid nucleus so that when fertilisation occurs the zygote will have the correct number of chromosomes

Question 21

What are ciliated epithelial cells and how are they specialised?

Answer 21

• ciliated epithelial cells line the surface of organs and contain hair-like structures called cilia and the top surface of the cell
• these are like short tails which move substances along the surface of the tissue
• the individual tails make the surface area larger
• these are found in the lining of airways to move mucus to the throat so that it goes to the stomach, getting killed by HCL rather than to the lungs
• they can also be found in the oviducts, transporting egg cells/ developing embryos towards the uterus

Question 22

What is diffusion?

Answer 22

• diffusion is the net overall movement of particles from an area of higher concentration to an area of lower concentration
• this is a PASSIVE PROCESS
• since it is moving from a high to low area of concentration, it is said that it moves down a concentration gradient
• it happens in both liquids and gases as the particles in these substances are able to move around freely
• when there is a cell membrane present only very small molecules can diffuse through like glucose, amino acids, water and oxygen. Bigger molecules like starch and proteins can’t fit through the membrane.

Question 23

What is osmosis?

Answer 23

• the net movement of water particles across a semi-permeable membrane from a region of high WATER concentration to a region of low WATER concentration.
• this is a PASSIVE PROCESS
• you could also say that it moves from a region of LOW SOLUTE CONCENTRATION to a region of HIGHER SOLUTE CONCENTRATION (not water)
  Explanation: if there was one side with only water molecules and low solute concentration (other substances other than water) the water molecules would move to the area with lower water concentration, the water concentration is lower because more of the concentration is being taken up by a solute like sucrose for example. As the water molecules flow into this high solute, low water conc. region the solute solution will get more dilute
• ## this moves down a concentration gradient as it is going high conc. to low conc.

Question 24

What is a partially permeable membrane?

Answer 24

• a membrane with very small holes so only tiny molecules like water can pass through them and bigger molecules like sucrose cannot.
• water molecules can pass through this membrane both ways during osmosis because water molecules can move around randomly at all times.

Question 25

What is active transport?

Answer 25

• active transport is the movement of particles across a membrane AGAINST a concentration gradient (from an area of low concentration to high concentration) using energy transferred during respiration.
• it requires energy as it is an ACTIVE process

Question 26

Why does active transport usually occur?

Answer 26

• cells may need to transport molecules against a concentration gradient or transport molecules that are too big to diffuse through a cell membrane.

Question 27

Describe how active transport is used in the digestive system.

Answer 27

• when there is a higher concentration of nutrients in the gut than in the blood, the nutrients will diffuse naturally into the blood
• but if there is a higher concentration of nutrients outside the gut, in the blood, rather than inside the gut, active transport allows nutrients to be taken into the blood by going against a concentration gradient.
• this stops us from starving.