Biology Paper 1

Eukaryotic Cell

Cell that has a nucleus and other membrane-bound organelles

Prokaryotic Cells

Genetic material is not enclosed in a nucleus. They are much smaller

An Animal cell contains...

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes

A plant cell contains...

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes, chloroplasts, cell wall, vacuole

Function of Nucleus

Enclose genetic material

Function of Cytoplasm

Liquid where chemical reactions occur

Function of cell Membrane

Control what enters and leaves the cell

Function of Mitochondria

Where aerobic respiration takes place

Function of Ribosomes

Site of protein synthesis

Function of chloroplasts

Contain chlorophyll and are the site of photosynthesis

Function of cell wall

Strengthen the cell; made of cellulose

Function of Vacuole

Full of cell sap; keeps the plant cells shape

Differentiation

The process of a cell becoming specialised; having a specific function

Sperm cells adaptations

Half the genetic material, long tail for swimming, lots of mitochondria for energy, contain egg-digesting enzymes

Nerve cell adaptations

Long axons carry impulses, myelin insulates and speeds up, synapse allow impulses to move, contains egg digesting enzymes

Muscle cell adaptations

Can contract, lots of mitochondria, wok together

Root hair cell adaptations

Large surface area to volume ratio, no chloroplasts

Xylem adaptations

No end walls, made from dead lignin cells

Phloem adatations

Have a companion cell to provide energy

Microscopes Practical

Use a slide and place it in microscopes on the lowest magnification. Focus the microscope while increasing the magnification.

Magnification =

size of image/size of real object

Electron Microscopes

Have a higher resolution and magnification. Can see in greater detail. they are more heavy, less portable and more expensive.

Bacteria

Multiply by Binary fission. About once every 20 minutes.

Practical: Antibiotics and bacteria

1. Sterilise area

2.Sterilise inoculation loop using fire

3. Open agar plate near flame

4. Spread Bacteria over plate

5. Place antibiotic paper in plate

6. Incubate for a few days at 25 degrees

Gametes

Sex cells that contain half the number of chromosomes

Chromosomes

Humans have 23 pairs of chromosomes. They carry genes

Cell Cycle

1. DNA replicates, the cell grows and copies internal structures

2. Mitosis takes place, cell splits

3. Two identical cells are formed

Stem cell

An undifferentiated cell which can give rise to more cells of the same type and can differentiate to form other types of cells

Stem cells Location

They are found in plant meristems, embryos and in bone marrows

Bone Marrow Transplant

Treat patients with leukaemia. The implanted stem cells divide to form new blood cells.

Therapeutic Cloning

A donor embryo is conceived to provide stem cells with the same genes for a patient.

Diffusion

The spreading out of particles resulting in a net movement from an area with a high concentration to an area of low concentration

Factors affecting the rate of diffusion

↑ concentration gradient ↑ diffusion

↑ temperature ↑ diffusion

↑ SA:V ↑ diffusion

↓ diffusion pathway ↑ diffusion

Osmosis

Diffusion of water from a dilute solution through a partially permeable membrane

Active Transport

Moves substances from a more dilute solution to a more concentrated solution against the concentration gradient.

Practical: effects of osmosis

1. Cut potato into equal-sized cubes

2. Measure mass and size of the cube

3. Put potato into 10cm3 of 0.5 molar sugar solution

4. Put potato into 10cm3 of 0.25 molar sugar solution

5. Put potato into 10cm3 of Water

6. Leave overnight

7. Measure mass and sizw again

Tissue

A group of cells with a similar structure and function

Organ

Group of tissues working together for a specific function

Digestion

Is the breaking down large insoluble molecules into small soluble molecules by enzymes

The digestive system contains

Mouth, oesophagus, stomach,small intestine, large intestine, liver, panaceas, rectum, duodenum

Function of mouth

Food is chewed here. Enzymes begin to break it up

Function of Oesophogus

Squeezes food down using peristalsis motion.

Function of Stomach

The digestion of proteins begins. It contains hydrochloric acid. Churning action make food into a fluid

Function of Small intestine

Absorbs nutrients(glucose, protein) from food.

Function of Large Intestine

Absorbs water from food

Function of Liver

Produces Bile

Function of Pancreas

Produces enzymes

Enzymes

Large protein molecules that catalyse chemical reactions without having any chemical change to themselves. Work at an optimum PH and temperature.

Protease

Breaks down proteins into amino acids. Made in the stomach, pancreas and small intestine.

Amalayse

Breaks down carbohydrates into starch. Made in the Salivary glands and the pancreas.

Lipease

Breaks down lipids into 3 fatty acids and 1 glycerol. Made in the pancreas and small intestine

Bile

Speeds up digestion of lipids. Stored in the Gall bladder. Emulsifies the lipids to increase the surface area that enzymes can work on and nutrilaises stomach acid

Hydrochloric acid

Provides the optimum PH for enzymes to work in the stomach.

Practical: PH and enzymes

1. Place a drop of iodine solution into each well of spotting tile

2. Get three test tubes and add

A - 2cm3 starch solution

B - 2cm3 amylase solution

C - 2cm3 PH 5 buffer solution

3. Place the test tubes in a 30C water bath

4. Mix the solutions and start timer

5. Every 30 secs add a drop of the mixed solution into a new well in the spotting tile

6. If starch is present it will turn blue, stop adding solution when it remains orange

7. Repeat using PH 6,7,8 buffers

Practical: Starch test

1. Place 2cm3 food solution in a test tube

2. Add a few drops of iodine

Present= turn blue black

Not present= stay orange

Practical: Sugar test

1. Place 2cm3 food solution in a test tube

2. Add 10 drops Benedict's solution

3. Place test tube in beaker of hot water

4. Leave for 5 minutes

Present = turn green/red

Not present = stay blue

Practical: Protein test

1. Place 2cm3 food solution in a test tube

2. Add 2cm3 of Biurets

Present = turn pink/purple

Not present = stay blue

Practical: Lipid test

1. Place 2cm3 food solution in a test tube

2. Add 3 drops Sudan III

3. Shake gently

Present = red stained oil layer will float to surface

Not present = stay red

Small intestine adaptations

Villi and Micro villi increase SA:V ratio

Good blood supply

Thin membrane