Biology Y7 Invertebrates; Keywords + Checklist

KEYWORD (Checklist Skill 1): Define “invertebrate”

An animal without a backbone.

KEYWORD (Checklist Skill 2): Define “annelid”

A phylum of invertebrates, in the animal kingdom, which includes segmented worms. (eg. earthworm)

KEYWORD (Checklist Skill 2): Define “cephalopod”

A class of invertebrates, in the phylum molluscs, including animals with distinctively larger bodies. (eg. squid, octopus)

KEYWORD (Checklist Skill 2): Define “mollusc”

A phylum of invertebrates, in the animal kingdom, including squids and octopus, which fall into the cephalopod class.

KEYWORD (Checklist Skill 2): Define “platyhelminth”

A phylum of invertebrates, in the animal kingdom, which include tapeworms and flatworms.

KEYWORD (Checklist Skill 3): Define “hydrostatic skeleton”

A type of skeleton that invertebrates which uses fluid instead of solid (bones) to help them move easier.

KEYWORD (Checklist Skill 5): Define “coelom”

A long, hollow compartment running through the length of an invertebrate’s (worm’s) body containing fluid, which forms the hydrostatic skeleton.

KEYWORD (Checklist Skill 5): Define “circular muscles”

A type of muscle in a worm’s anatomy which encircles the coelom to help move fluid in the coelom, making it a major part of a hydrostatic skeleton.

KEYWORD (Checklist Skill 5): Define “longitudinal muscles”

A type of muscle in a worm’s anatomy which runs across the worm’s length to help move fluid in the coelom, making it a major part of a hydrostatic skeleton.

KEYWORD (Checklist Skill 5): Define “clitellum”

A thicker and smoother segment of a worm which secretes egg sacs and creates cocoons where embryos are made.

KEYWORD (Checklist Skill 5): Define “chaetae”

Tiny bristles on the ventral side of a worm to grip the ground to aid movement.

KEYWORD (Checklist Skill 7): Define “siphon”

A gap in a squid which propels water for jet propulsion, locomotion and respiration.

KEYWORD (Checklist Skill 6): Define “jet propulsion”

The process used by squids to move by drawing water into the mental cavity, then to the siphon to get expelled, propelling the squid in the opposite direction of the water’s movement.

KEYWORD (Checklist Skill 8): Define “parasite”

An organism that lives in or on another for its own benefit. (to gain food/transmit disease)

KEYWORD: Define “tapeworm”

A parasite of the platyhelminth phylum of the animal kingdom which live in the small intestine to suck nutrients.

What are the first 3 ranks of classifying an animal?

1. Kingdom (animal)

2. Phyla (mollusc)

3. Class (cephalopod)

DEFINITON: phylum, phyla

Scientific word for group/type when classifying animals.

__% of animals are classed as invertebrates.

95%

How do earthworms move with a hydrostatic skeleton? (KEY SKILL 4)

Earthworms move with a hydrostatic skeleton by effectively moving the fluid in their coelom, using an antagonistic muscle group of the circular and longitudinal muscles which encircle the coelom or run across the length of the worm.

What are the meanings of:

• Dorsal

• Ventral

• Anterior

• Posterior

• Dorsal: Upper side/back of an organism

• Ventral: Underside of an organism

• Anterior: Front end of an organism

• Posterior: Rear end of an organism

How do squids use jet propulsion to move?

1. They draw water into their mantle cavity (an opening in the mantle)

2. Then, the water travels to the siphon which closes the mantle cavity flaps.

3. Finally, the water gets expelled from the siphon, propelling the squid in the opposite direction (of the water).

What direction does a squid move in jet propulsion compared to the water?

A squid moves at the opposite direction of the water gets expelled from the siphon. (similar to a balloon)

What features of a squid are used for jet propulsion?

• Mantle cavity

• Siphon

Where do tapeworms live?

They live in the small intestine of humans and many animals.

What is diffusion?

The process of which tapeworms absorb food that is already digested from the skin of the small intestine.

What adaptations do tapeworms have for a parasitic lifestyle?

• Suckers and hooks on its head to attach to the intestine wall of the host, preventing it from being lost in faeces.

• Long, flattened body to increase surface area and the absorption of digested food.

• Thin body wall to shorten the distance for faster diffusion.

Humans can be infected by ____ and _____ tapeworms.

pork, beef

State the life cycle of a tapeworm.

1. Humans eat meat that has been infected with tapeworm eggs from an infected animal.

2. Tapeworms get egested and go into human faeces.

3. Animals eat infected human faeces on vegetation, infecting the animal with tapeworms.

4. Tapeworms develop in the infected animal, with the infected animal being used for meat, for humans to eat, giving humans infected meat.

What is Stage 1 of the tapeworm life cycle?

Humans eat meat infected with tapeworm eggs from an infected animal.

What is Stage 2 of the tapeworm life cycle?

Tapeworms get egested and go into human faeces.

What is Stage 3 of the tapeworm life cycle?

Animals eat infected faeces in their vegetation, which leads to the animal being infected with tapeworms.

What is Stage 4 of the tapeworm life cycle?

Tapeworms develop in the infected animal, with the infected animal being used for meat, for humans to eat, giving humans infected meat.

1. What class of invertebrates are highly intelligent?

2. What phylum are they?

Q1+2 ARE LIKELY ANSWERS

Cephalopods

Molluscs

3. What are the spherical structures in the middle of the cells?

4. Are they prokaryotic or Eukaryotic?

Q3 IS A LIKELY ANSWER

3. Nucleus

4. Eukaryotic

5. What are the features on the tapeworm’s head?

Q5 IS THE LIKELY ANSWER

Suckers and hooks

6. Suggest why a student infected with tapeworms has a tummy ache.

As tapeworms live in the small intestine which is a part of the digestive system which links to digestion issues which links to having a tummy ache.

7. Label and name the muscle groups of a worm.

Q7 IS A LIKELY ANSWER

Circular/longitudinal muscles

9. What type of skeleton does a worm have?

Q9 IS A LIKELY ANSWER

Hydrostatic skeleton

10. A tapeworm when in a human can lay up to 50,000 eggs. 85% hatch successfully and 4% of the hatched eggs will infect another human.

FORM A WORDED EQUATION.

4% of 85% of 50,000

11. What are the 4 steps of lifecycle in a tapeworm?

1. Humans eat meat that has been infected with tapeworm eggs from an infected animal.

2. Tapeworms get egested and go into human faeces.

3. Animals eat infected human faeces on vegetation, infecting the animal with tapeworms.

4. Tapeworms develop in the infected animal, with the infected animal being used for meat, for humans to eat, giving humans infected meat.

12. What needs to be improved in the cooking of meat to avoid parasites?

The internal temperature of the meat has to be warm enough to kill any parasite eggs.

What is the difference between a parasite, pest and pathogen?

A parasite is an organism which lives in or on another to gain benefit.

A pest is something that annoys you.

A pathogen is a microbe which causes disease.

What does a good parasite do?

• Gets benefit from the host without killing it.

• Avoids the host’s immune system.

• Has a rapid life-cycle completion.

• Has effective ways of transmitting each other/disease.

Why do tapeworms live in the small intestine?

Because the food in the small intestine is already digested and its nutrients can be absorbed directly by the tapeworm. (diffusion)

What is a host in biology? (in terms of this topic)

An organism which benefits the parasite.

Define “transmission”

The process of a disease/parasite spreading from one host to another.

What are the stages of tapeworm growth?

Define cyst.

Cyst —> Larvae —> Tapeworm

Cyst: egg protected by jelly with tapeworm egg, the jelly is broken down by stomach which releases the tapeworm!

In a squid, the ________ are ________ than arms.

tentacles, longer

List the major external organs of a squid.

• Eye

• Tentacles/arms

• Mantle (+ mantle cavity)

• Siphon

• Suckers

• Fins

What is the eye used for in a squid?

To have visual perception and detection of light.

What are the tentacles/arms used for in a squid?

To grasp and hold prey.

What is the mantle used for in a squid?

To encase the body and house internal organs.

What is the siphon used for in a squid?

To propel water for jet propulsion and respiration.

What is the suckers used for in a squid?

To manipulate food, aid movement and reproduction.

What is the fins used for in a squid?

To manoeuvre and stabilize the body.

What are the eyes located on a squid?

The side of the head.

What are the tentacles/arms located on a squid?

The 2 tentacles are at the end of the squid sticking out as the longer limbs while the arms are the shorter limbs sticking out from their mouth.

What is the mantle and siphon located on a squid?

The mantle is the outer layer of the squid encasing the organs.

The siphon is the tube on near mantle of the squid.

What are the suckers located on a squid?

On the end of the tentacles and arms

What are the fins located on a squid?

To both sides of the mantle.

Label the features of a squid on the diagram from their numbers.

1. Arm

2. Tentacle

3. Eye

4. Sucker

5. Siphon

6. Mantle

7. Fin

What is the major internal organ for a hydrostatic skeleton in an earthworm?

Coelom

Where is the gut and coelom of an earthworm?

The gut is the tube in the centre running through the earthworm.

The coelom surrounds the gut whilst being covered by the earthworm’s skin and circular/longitudinal muscles.

EARTHWORM INTERNAL: Label the numbers with their selective organs on the diagram

1. Pharynx

2. Hearts

3. Oesophagus

4. Crop

5. Dorsal blood vessel

6. Gizzard

7. Intestine

8. Clitellum

List some major anatomy/muscle groups of an earthworm

Pharynx

Hearts

Oesophagus

Crop

Dorsal blood vessel

Gizzard

Intestine

Clitellum

Circular/longitudinal muscles

Coelom

Chaetae

Seminal vesicles

EARTHWORM INTERNAL: Where is the pharynx and what does it do?

It is the light-coloured organ inside the mouth which passes food down to the oesophagus.

EARTHWORM INTERNAL: Where is the crop and what does it do?

It stores food from the oesophagus and is in the digestive system after the oesophagus.

EARTHWORM INTERNAL: Where is the gizzard and what does it do?

It breaks down food which comes from the crop in the digestive system.

EARTHWORM INTERNAL: Where is the intestine and what does it do?

A long tube extending from the gizzard to the anus which digests and absorbs food.

EARTHWORM INTERNAL: Where are the hearts and what does it do?

Behind the pharynx as five dark loops which are blood vessels that act as a worm’s heart.

EARTHWORM INTERNAL: Where is the dorsal blood vessel and what does it do?

A dark line extending from the hearts to the top of the crop, linking them.

EARTHWORM INTERNAL: Where are the seminal vesicles and what does it do?

The light coloured tissue above and around the heart which produce sperm and form the reproductive system.

How do earthworms use their antagonistic muscle group to move? (KEY SKILL 4)

They use their circular and longitudinal muscles to move the fluid in their coelom.

What happens when the circular muscles contract? (KEY SKILL 4)

As the circular muscles which encircle the coelom contract, the worm gets thinner and longer pushing the fluid in the coelom forward.

What happens when the longitudinal muscles contract? (KEY SKILL 4)

As the longitudinal muscles contract, the worm gets shorter and fatter, pulling the posterior end forward, with the chaetae providing grip and efficient movement.