Topic 1 - Key Concepts

Key Concepts of Biology

What are eukaryotic cells?

Cells with a nucleus like plant and animal cells.

What are prokaryotic cells?

Cells without a nucleus like bacteria.

Compare prokaryotic and eukaryotic cells

Prokaryotic - Cells without a nucleus like bacteria. They are smaller and simpler.

Eukaryotic - Cells with a nucleus like animals. They are larger and more complex.

Are prokaryotes smaller or bigger than eukaryotes?

Smaller

Are eukaryotes smaller or bigger than prokaryotes?

Bigger

Are prokaryotes more complex or simpler than eukaryotes?

Simpler

Are eukaryotes more complex or simpler than prokaryotes?

More complex

Are animal cells eukaryotic or prokaryotic?

Eukaryotic

Are plant cells eukaryotic or prokaryotic?

Eukaryotes

Are animal cells prokaryotes or eukaryotes?

Eukaryotes

Are plant cells prokaryotes or eukaryotes?

Eukaryotes

List the 5 organelles found in an animal cell

• Cell Membrane

• Nucleus

• Ribosomes

• Mitochondria

• Cytoplasm

List the 8 organelles found in an plant cell

• Cell Membrane

• Cytoplasm

• Nucleus

• Mitochondria

• Ribosomes

• Cell wall

• Chloroplasts

• Permanent vacuole

Which 3 organelles does a plant cell have that an animal cell doesn’t?

• Cell wall

• Chloroplasts

• Permanent vacuole

What is the function of the nucleus?

Controls the activities of the cell + stores DNA (genetic information).

What is the function of the cell membrane?

Controls what enters and exits the cell.

What is the function of the mitochondria?

Site of aerobic respiration to release energy to the cell.

What is the function of the ribosomes?

Site of protein synthesis.

What is the function of the cytoplasm?

Jelly like substance where chemical reactions take place + holds other cells in place.

What is the function of the cell wall?

Supports/Strengthens the cell + Made of cellulose in plant cells.

What is the function of the chloroplasts?

Contains chlorophyll (green pigment) to absorb light energy for photosynthesis to take place here.

What is the function of the permanent vacuole?

Cell sap stored here + maintains shape of the cell

What is the cell wall made out of in plant cells?

Cellulose

Is a plant cell wall made of cellulose?

Yes

What is the difference between a cell membrane and cell wall?

Cell membrane - Controls what enters and exits the cell.

Cell wall - Made out of cellulose to support and strengthen the cell.

Why do plant roots not require chloroplasts?

They are underground and cannot photosynthesise without sunlight so therefore do not require chloroplasts.

List the 8 organelles found in bacterial cells

• Cell Membrane

• Cell Wall

• Slime coat

• Plasmid DNA

• Chromosomal DNA

• Flagella

• Ribosomes

• Cytoplasm

Are bacteria cells prokaryotes or eukaryotes?

Prokaryotes

Is bacteria uni or multicellular?

Unicellular

Does bacteria have a jelly or slime coat?

Slime coat

What are the two types of DNA found in bacterial cells?

Plasmid DNA + Chromosomal DNA.

What is plasmid DNA?

Small circular loops of DNA with useful genes.

What is chromosomal DNA?

Large pieces of DNA floating in the cytoplasm.

What is the function of the flagellum?

Tail used to help the cell move.

What is the function of the slime coat?

Protects the bacteria cell.

Is a bacterial cell smaller or bigger than animal/plant cells?

Smaller

Is a bacterial cell wall made of cellulose?

No

Define: Specialised cell

Cells adapted to carry out a particular function in the body.

What is the egg cell?

Female gamete

What is the female gamete?

Egg cell

What is the function of the egg cell?

Carry female DNA + Develop into an embryo.

What adaptations do egg cells have?

• Cytoplasm

• Haploid nucleus

• Cell membrane

• Jelly coat

What is a sperm cell?

Male gamete

What is the male gamete?

Sperm cell

What is the function of the sperm cell?

Fertilise egg cell + Transport male’s DNA to egg cell.

What adaptations do sperm cells have?

• Flagellum

• Mitochondria

• Acrosome

• Haploid nucleus

What is a haploid nucleus?

Nucleus containing half the number of chromosomes as a diploid nucleus (23 chromosomes)

What is the name of a nucleus containing 23 chromosomes?

Haploid nucleus

How many sets of chromosomes does a haploid cell have?

1 set

What is a diploid nucleus?

Nucleus containing 23 pairs of chromosomes (46 chromosomes)

What is the name of a nucleus containing 46 chromosomes?

Diploid nucleus

How many sets of chromosomes does a diploid cell have?

2 sets

What type of nucleus does a sperm cell have?

Haploid

What type of nucleus does an egg cell have?

Haploid

Why do gametes need a haploid nucleus?

So when the gametes join to form a zygote it will have a diploid nucleus (2 sets, 23 pairs, 46 chromosomes).

Why do sperm need flagellum?

To move to the egg cell and fertilise it.

Why do sperm cells have lots of mitochondria?

So they can respire to release energy to the cell and move to the egg cell to fertilise it.

What does the acrosome contain?

Digestive enezymes

What is the function of the acrosome?

Contains digestive enzymes to break down the egg cells cell membrane + jelly coat.

How can we describe a sperm cells head?

Streamlined head

What does the head of the sperm cell contain?

Acrosomes

How does a streamlined head help a sperm cell to function?

Head of the sperm cell containing acrosomes to penetrate the egg cell.

What is the function of the cytoplasm in the egg cell?

Contains nutrients for the growth of the embryo.

Does an egg cell have a jelly or slime coat?

Jelly coat

What does the cell membrane/jelly coat do after fertilisation?

They harden so only 1 sperm cell can enter the egg cell.

Why does only 1 sperm cell enter the egg cell?

Cell membrane/jelly coat harden after fertilisation, not allowing any sperm through.

Why do egg cells not need a tail?

Cilia sway to move the egg from the oviduct to the uterus.

Describe how the egg cell is adapted for its function

• Cell membrane/Jelly coat - Hardens after fertilisation so only 1 sperm can enter.

• Cytoplasm - Contains nutrients for developing embryo.

• Haploid nucleus - Contains half of the DNA (23 chromosomes) so when it merges with the sperm cell, it forms a zygote with a diploid nucleus (46 chromosomes).

Describe how the sperm cell is adapted for its function

• Flagellum - Tail to move towards the egg cell and fertilise it.

• Lots of mitochondria - Provides energy for the cell to swim towards the egg cell.

• Acrosome - Contains digestive enzymes to break down the egg cells cell membrane + jelly coat.

• Haploid nucleus - Contains half of the DNA (23 chromosomes) so when it merges with the sperm cell, it forms a zygote with a diploid nucleus (46 chromosomes).

What are ciliated cells?

A cell that lines certain tubes in the body and has cilia on its surface.

Where are ciliated cells found?

Oviducts and respiratory system.

What adaptations do ciliated cells have?

Cilia

What are cilia?

Microscopic hairs that sway to move substances/particles.

Describe how the ciliated epithelial cell is adapted for its function

Has microscopic hairs called cilia that sway to move substances like mucus up the throat.

What adaptations do the small intestines have?

Microvilli

What is found in the small intestine?

Villi/Microvilli and Capillaries

What are the villi?

Folds in the small intestine.

What are the microvilli?

Microscopic folds in the small intestine.

How do microvilli increase the rate of absorption in the small intestine?

Have a large surface area to increase rate of absorption/diffusion of substances.

How do capillaries increase the rate of absorption in the small intestine?

They increase blood supply to increase rate of absorption of nutrients.

Describe how the small intestine is adapted for its function

• Viili + Microvilli. These adaptations massively increase the surface area of the small intestine, allowing absorption of nutrients into the blood to take place faster and more efficiently.

• Villi have a thin cell membrane to increase the rate of absorption of nutrients into the blood.

• Capillaries provide a good blood supply in the villi so that nutrients can be absorbed quickly.

What is the role of a microscope?

To magnify cells so that we can see the actual structures in more detail.

Where is the slide viewed from on microscope?

Stage

What is the function of the stage?

Where the slide is viewed from.

Which lens on a microscope do we look through?

Eyepiece lens

Which lens on a microscope magnifies the image?

Objective lens

What is the function of the eyepiece lens?

To look through.

What is the function of the objective lens?

To magnify the image.

Which wheel on a microscope raises and lowers the stage?

Coarse focus wheel

Which wheel on a microscope sharpens the image under high magnification?

Fine focus wheel

What is the function of the coarse focus wheel?

Raises and lowers the stage.

What is the function of the fine focus wheel?

Sharpens the image under high magnification.

Which sort of the microscope controls the amount of light?

Diaphragm

What is the function of the diaphragm on a microscope?

Controls the amount of light.

Describe the steps of the Microscopes Core Practical

• Peel one one cell layer of skin from an onion using a scalpel/tweezers.

• Place specimen on a microscope slide. Add a drop of iodine to stain the cells, making them visible.

• Place a coverslip over the specimen to keep it flat and in place. Then place slide on the stage.

• Turn on the light using the diaphragm and start on the lowest objective lens.

Why should the cell we are looking at under the microscope be very thin?

So the light can pass through it.

What do we place the specimen on?

A slide

Which stain do we place on the specimen when using microscopes?

Iodine

Why do we place iodine over the specimen?

To make cells visible.

What we place over the slide/specimen?

Coverslip