BIOLOGY

What does Mitosis do?

Provides new cells for growth and repair of damaged tissues and maintains the diploid chromosome complement.

Why is it important that the diploid chromosome complement is maintained?

To ensure that daughter cells contain the same genetic information as the parent cell.

Steps to Mitosis

1. Long uncoiled chromosomes double to form two identical chromatids.

2. Chromosomes shorten and become visible. Nuclear membrane disappears.

3. Chromosomes line up at the equator and spindle fibres attach.

4. Chromatids are pulled apart and chromosome move to opposite poles.

5. Nuclear membrane forms and cytoplasm divides.

6. Two identical daughter cells are produced.

Stem cells in ANIMALS are…

unspecialised cells which can divide in order to self renew. They are also involved in growth and repair.

Stem cells can be obtained from…

the embryo at a very early stage or in the body throughout life.

EMBRYONIC stem cells can become…

any cell type.

TISSUE stem cells can become…

some cell types.

Multicellular organisms have…

more than one cell type and are made up of tissues and organs.

The cells in organs are…

specialised for their function and work together to form systems.

Specialisation of cells…

leads to the formation of a variety of cells, tissues, and organs.

Cells ➡ Tissues ➡ …

Organs ➡ Systems ➡ Organisms.

What is the function of the MEDULLA?

Controls breathing and heart rate.

What is the function of the CEREBELLUM?

Controls balance and coordination of movement.

What is the function of the CEREBRUM?

Site of conscious thought, memory, and emotion.

A nerve cell is known as a…

neuron.

What does a Sensory Neuron do?

Passes information from receptors to the CNS.

What does an Inter Neuron do?

Operate within the CNS which processes information that requires a response.

What does a Motor Neuron do?

Carries electrical impulses from the CNS to the effector, like muscles or glands, to enable a response.

What carries messages along neurons?

Electrical impulses.

A response to a stimulus can be a RAPID ACTION from a…

muscle.

A response to a stimulus can be a SLOWER RESPONSE from a…

gland.

Steps to Nerve Impulse.

1. Receptor detects stimulus.

2. Sensory neurons pass the information to the CNS.

3. Inter neurons operate within the CNS, which processes information that require a response.

4. Motor neurons enable a response to occur at an effector which may be a muscle or gland.

Chemicals called neutrotransmitters…

transfer messages between neurons at synapses.

Reflexes protect…

the body from harm.

Steps to a Reflex Arc.

1. A receptor will detect a stimulus e.g. heat.

2. The sensory neuron will transmit an electrical impulse to the CNS.

3. Message is passed across synapse to inter neuron in the spinal cord. Information is also sent to the brain.

4. Electrical impulses carry the response along the inter neuron in the spinal cord. Message is passed across synapse by neurotransmitters to the motor neuron.

5. Motor neuron carries response to the effector e.g. pull hand away.

6. The effector moves the hand away from the stimulus.

Hormones are ___ _____ which are released by _____ ___ into the bloodstream.

Chemical Messengers, Endocrine Glands.

Hormones are specific to certain…

target tissues.

Target tissues have…

cells with complementary receptor proteins so only that tissue will be affected by the hormone.

It is important that cells have a constant supply of glucose for…

respiration.

If the concentration of glucose in the blood is TOO HIGH…

diabetes may develop.

If the concentration of glucose in the blood is TOO LOW…

respiration may be limited.

What two hormones does the body use to regulate blood glucose concentration (BGC)?

Insulin and Glucagon.

INSULIN promotes the conversion of…

glucose in the bloodstream into glycogen in the liver.

GLUCAGON promotes the conversion of…

glycogen to glucose.

If blood glucose concentration DECREASES…

• Change is detected by receptor cells in pancreas.

• Pancreas releases more glucagon and less insulin.

• Liver cells break down glycogen to glucose and release it to bloodstream.

• BGC increases and goes back to normal.

If blood glucose concentration INCREASES…

• Change is detected by receptor cells in pancreas.

• Pancreas releases more insulin and less glucagon.

• Liver cells take up more glucose from blood and convert it to glycogen.

• BGC decreases and goes back to normal.

Diploid:

Two matching sets of chromosomes.

Haploid:

One set of chromosomes.

All cells are ___ except from gametes which are ___.

Diploid, Haploid.

Testes:

Site of gamete (sperm) production.

Urethra:

Carries sperm and urine to the penis.

(Seminal) glands:

Produces semen.

Penis:

Allows sperm to reach the vagina or urine to exit the body.

Ovary (human):

Site of egg production/storage.

Oviduct:

Site of fertilisation.

Vagina:

Where sperm enters the body.

Uterus:

Site of foetal development.

Definition of Fertilisation:

The fusion of the nuclei of the two haploid gametes to produce a diploid zygote, which divides to form an embryo.

The male gamete in plants…

is pollen which is produced in the anthers.

The female gametes in plants…

are ovules which are produced in the ovary.

Ovary (plants):

Site of female gamete production in plants.

Anther:

Site of male gamete production in plants.

Pollen:

Male gamete in plants.

Ovule(s):

Female gamete in plants.

Gene:

A gene is a section of DNA that codes for a specific protein.

Alleles:

Different versions of the same gene e.g. eye colour.

Genotype:

An individuals alleles for a particular characteristic.

Phenotype:

Physical characteristic caused by the genotype.

Dominant:

A type of gene which can mask a recessive gene.

Ressesive:

A type of gene which can be masked by a dominant gene.

Homozygous:

Having two of the same alleles for the same trait (characteristic) e.g. TT or bb.

Heterozygous:

Having two diffrent alleles for the same trait (Bb)

Variation:

Differences between individual members of the same species.

Two types of variation:

• Discrete

• Continuous

Discrete Variation:

Where measurements fall into distinct groups.

This is single gene inheritance (controlled by one gene).

Continuous Variation:

Where measurements exist as a range of values between a minimum and a maximum.

This is polygenic inheritance (controlled by many genes).

The more ___ present in a population, the more ___ within the population.

• Alleles

• Variation

Upper Epidermis:

Top of leaf

Palisade Mesophyll:

Site of light capture for photosynthesis

Spongy Mesophyll:

Site of gas exchange

Vein (plant):

Contains xylem and pholem which allow the transport of water and sugar.

Lower Epidermis:

Bottom of leaf

Guard Cells:

Change shape to open or close stomata.

Stomata:

Pores which allow carbon dioxide to enter and water + oxygen to leave

Veins are made up of ___ and ___.

• Xylem

• Pholem

Xylem are dead cells which…

carry water and minerals through the stem to the leaves.

Xylem are lignified with…

rings of lignin so they don’t break as the pressure changes when water moves through the plant.

Sugar is made during ____ in the ____ ___ cells of the leaves.

• Photosynthesus

• Palisade Mesophyll

Plant Organs:

• Leaf

• Stem

• Roots

Uses of water in plants:

• Photosynthesis

• Transport of minerals and sugar

• Support

• Cooling through evaporation

Definition of Transpiration:

The process of water moving through a plant and its evaporation through the stomata.

Process of Transpiration:

1. Plants absorb water and minerals through their roots by osmosis.

2. The water and minerals are then transported up the stem to the leaves through xylem at high pressure.

3. If the stomata are open, water vapour will diffuse out of the leaf.

The function of blood is to transport…

nutrients, oxygen, and carbon dioxide.

In mammals, blood is made up of:

• Platelet

• Red blood cell

• White blood cell

• Plasma

Two main types of white blood cells:

• Phagocytes

• Lymphocytes

Function of Phagocytes:

To carry out phagocytosis by engulfing and digesting pathogens. e.g. bacteria, viruses, and fungi.

Function of Lymphocytes:

To produce antibodies which destroy pathogens. Each antibody is specific to a particular pathogen.

Pulmonary Vein:

Carries oxygenated blood from the lungs to the left atrium.

Left Atrium:

Passes blood from pulmonary vein to the left ventricle.

Left Ventricule:

Passes blood from the left atrium to the Aorta.

Aorta:

Carries oxygenated blood at high pressure around body.

Vena Cava:

Returns deoxygenated blood to the heart

Right Atrium:

Passes blood from vena cana to the right ventricle.

Right Ventricle:

Passes blood from the right atrium to pulmonary artery.

Pulmonary Artery:

Carries deoxygenated blood to lungs.

Valves:

Prevents back flow of blood.

Coronary Arteries:

Supplies the heart tissue with oxygen.

Red blood cells have a ____ shape and no ____.

• Biconcave

• Nucleus

Red blood cells contain _____ which allows them to transport ____ in the form of _____.

• Haemoglobin

• Oxygen

• Oxyhaemoglobin

White blood cells are part of the ____ system and are involved in destroying ____.

• Immune

• Pathogens