Cell structure

Microscopes are used in biology to see objects too small for the human eye.

A student makes a microscope slide of a layer of onion epidermal cells.

The student uses a coverslip to make the slide.

Describe the function of the coverslip.

When the student looks down the microscope, they see an image like the one below.

Identify subcellular structure X and describe its function.

The student prepared the slide by covering the onion epidermal cells with water.

The student looks at the cells again after one hour and the vacuoles look larger.

Explain why the vacuoles look larger.

Use your knowledge of transport in cells.

Name the sub-cellular structure which stores the genetic material in an animal cell.

Complete the sentences to describe the genetic material.

Use words from the list.

diploid genes genome genotype

haploid heterozygous homozygous variation

The entire genetic material of an organism is called the........

Human body cells have 23 pairs of chromosomes because they have two copies of each

chromosome. These cells are called........

Human gametes have only 23 chromosomes. These cells are called........

Most observable characteristics are the result of multiple........

Which sub-cellular structure is not found in eukaryotic cells?

A Chloroplast

B Nucleus

C Plasmid

D Ribosome

The image shows cheek cells magnified at 550×.

Calculate the actual length of the cell marked X.

Use the line on the image.

State the function of the sub-cellular structure labelled Y.

Plasmids are small rings of genetic material.

Which row describes where plasmids are found?

What are two characteristics of a cell membrane?

A Non-selective barrier and contains plasmids

B Non-selective barrier and contains receptors

C Selective barrier and contains plasmids

D Selective barrier and contains receptors

Genetic material is required for inheritance in eukaryotic and prokaryotic cells.

Compare the genetic material found in eukaryotic and prokaryotic cells.

Peas develop inside pods.

Pea pods are either green or yellow. The allele for green is dominant over the allele for yellow.

The table shows some information about three different pea pods.

Complete the table.

A gardener crosses a plant that has green pods with a plant that has yellow pods. The gardener thinks both these plants have a homozygous genotype.

The result is 15 new plants with green pods and 3 plants with yellow pods.

Show that the gardener’s green plant did not have a homozygous genotype by completing the two genetic diagrams.

Use letters G and g for the alleles.

If the green plant has a homozygous genotype:

If the green plant does not have a homozygous genotype:

The ratio the gardener achieved was 5 green to 1 yellow.

Suggest why this does not match either of the offspring ratios.

The diagram shows a prokaryotic cell.

Which structure labelled in the diagram would not be found in a eukaryotic plant cell?

Tick (✓) one box.

Prokaryotic cells are much smaller than most eukaryotic plant cells.

Explain why an electron microscope is used to view smaller prokaryotic cells instead of a light microscope.

Some prokaryotic cells contain chlorophyll in their cytoplasm.

Where is chlorophyll found inside eukaryotic plant cells?

What are plasmids?

A Genetic material found in the cytoplasm of a eukaryotic cell.

B Genetic material found in the cytoplasm of a prokaryotic cell.

C Genetic material found in the nucleus of a eukaryotic cell.

D Genetic material found in the nucleus of a prokaryotic cell.

Which row shows correct information about cell membranes?

Which part of the cell provides a selective barrier to molecules entering the cell?

A Cell membrane

B Cell wall

C Cytoplasm

D Plasmid

Fig. 16.1 shows a single-celled organism called an alga.

The alga cell is a eukaryotic cell.

Describe two differences in structure between eukaryotic and prokaryotic cells.

Explain why chloroplasts are needed for photosynthesis.

Fig. 16.2 shows algae growing on the surface of a lake.

In the summer the area covered by the algae increases.

Other plants growing at the bottom of the lake receive less light.

Explain how this could affect the growth of the plants at the bottom of the lake.

Compare the process of photosynthesis with the process of aerobic respiration.

HIV is a virus that causes AIDS.

HIV infects human cells by inserting genes into the cells. The human cells then copy the genes.

In which part of a human cell are HIV genes copied?

chloroplast cytoplasm mitochondria nucleus

In the laboratory, scientists have used gene technology to completely remove HIV genes from infected cells.

Explain how removing HIV genes could affect the spread of HIV.

Suggest why some people are concerned about the use of gene technology in HIV treatment.

The Human Genome Project mapped the human genome.

Write down what is meant by the term genome.

Knowledge of the human genome could identify the genes affected by HIV.

Write down two ways knowledge of the human genome could help with the treatment of HIV.

*(d) Some countries have set up centres where a person is counselled and tested for HIV.

The aim is to reduce new infections by 50%.

Describe how HIV is transmitted and how these centres can contribute to reducing the spread of HIV.

HIV invades white blood cells stopping them working.

Describe the role of white blood cells in the defence against disease.

Look at the diagram of a bacterial cell.

What is the name of the structure labelled X ?

A Mitochondrion

B Nucleus

C Plasmid

D Receptor molecule

The drawing shows some of the structures found in an animal cell.

Which labelled structure contains enzymes for cellular respiration?

The picture shows plant cells as seen using a light microscope.

Draw a large labelled diagram of cell X.

The plant cells shown in Fig. 11.1 are not root cells.

Explain how you can tell this from the picture.

A plant is growing in a soil of pH 4.

Which mineral ion will be most available to the plant?

Magnesium is required by plants for photosynthesis.

Growing plants in very alkaline soils may result in less biomass.

Use the chart to explain why.

The picture shows a root growing from a seed.

Explain how the structures seen on the root help with the uptake of minerals.

Complete these sentences about the hormone FSH.

FSH is secreted by the........ gland.

FSH causes an........ to mature in the ovary.

FSH stimulates the ovaries to release the hormone........

FSH hormone can be genetically engineered.

The human gene for FSH is transferred into an animal cell.

Look at the diagram of a cell.

The gene is put inside one of the structures labelled in the diagram.

Which structure is the gene put inside?

Choose from A, B, C, or D........

State why the gene is put there.

* Beta carotene is the substance that makes carrots orange. Humans use beta carotene to make vitamin A. Vitamin A is needed for good vision.

‘Golden’ rice is a genetically modified (GM) crop. ‘Golden’ rice is made when the gene for beta carotene is added to rice.

Scientists do not know if the levels of beta carotene in ‘Golden’ rice will have any other effects on people eating the rice.

In some countries many people survive on a diet of mainly rice with no vegetables.

Do you think ‘Golden’ rice should be made to provide food for these people?

Include arguments for and against ‘Golden’ rice in your answer.