Yr 10 Half Yearlys

Question 1

Fossil

Answer 1

are traces of past life preserved in soils or rocks

Question 2

Palaeontology

Answer 2

is the study of past life

Question 3

The fossil record

Answer 3

the fossil record is a record made consisting of all the fossils that have been discovered, together with their relative ages. Fossils are a rare occurrence and the fossil record is incomplete.

Question 4

How do different preserving environments result in different types of fossil

Answer 4

Some environments suit the formation of fossils such as shallow lakes and seas. Some parts of organisms like bones and shells fossilise more readily than soft tissues and tiny bacteria.

Question 5

Permafrost

Answer 5

near the Arctic Circle, the land is almost frozen. Bacteria and fungi that cause decay cannot grow if the temperature is below freezing.

Question 6

Amber

Answer 6

amber is solid plant sap or gum. When amber sets and hardens, it can preserve whatever is entombed inside it.

Question 7

Tar

Answer 7

tar pits occur when oil seeps out of the ground and onto the surface. Many animals such as mammoths and sabre-toothed cats became stuck in the sticky tar, leaving them to die there and become fossilised

Question 8

Peat

Answer 8

the layers of peat can be very deep and oxygen and bacteria are often absent in the lowest layers. This gives the soft tissue trapped in these layers a chance of being preserved. The peat is generally acidic and this dissolves the hard minerals in the bone, making them very soft

Question 9

Dry air

Answer 9

dry air dehydrates the soft tissue, which fossilised, and turns it into a ‘mummy’. The mummified skin then forms a mould in sediments.

Question 10

Explain the fossil record being incomplete

Answer 10

due to the nature of many organisms (small and/or no hard parts) and the low chance of being fossilised after death, due to scavengers and being in the wrong place

Question 11

Define relative dating

Answer 11

Relative dating is the process of determining if one rock or geologic event is older or younger than another, without knowing their specific ages.

Question 12

How does relative dating work

Answer 12

compares the ages of one fossil or rock with another to determine which is older. The process relies on two assumptions: sedimentary rocks form in layers, fossils are the same age as the rocks in which they are found.

Question 13

State the characteristics of index fossils

Answer 13

Index fossils are fossils used to define and identify geological periods
To be used as an index fossil, the species must have been fairly widespread, lived in a fairly narrow period of time, been abundant and been easy to identify. They can be used to accurately compare and date the ages of strata in different locations using relative dating.

Question 14

Characteristics of index fossils such as trilobites and explain why these can date rock layers.

Answer 14

Trilobites evolve rapidly, and like other arthropods, trilobites serve as excellent index fossils, enabling geologists to date the age of the rocks in which they are found.

Question 15

Define stratigraphy

Answer 15

the science of comparing rock layers (strata) to gain information about the history of the earth.

Question 16

Explain how stratigraphy is based on the use of index fossils

Answer 16

Sediments fall due to gravity and form horizontal layers.
The materials the layers are made from can be studied and any fossils within these layers can be used to determine a relative age for the rocks.

Question 17

Define absolute dating

Answer 17

the process of determining an age on a specified chronology.

Question 18

Explain how radioactive decay is used to date rocks and fossils.

Answer 18

Some elements have isotopes which are radioactive so they release particles and energy in a steady stream to become stable in a process known as radioactive decay.
The half-life of an element is the time it takes for half of the radioactive sample to decay to a new element.
A sample of rock can be taken and analysed to compare the proportion of original radioactive particles to new particles it contains. Once this is measured we can use this to determine how long the sample has existed or its age.

Radioisotopes decay at a known rate and this rate of decay can be used to estimate how long ago a rock was layed down.

Question 19

Outline the fossil history of the vertebrates, emphasising the stage when life spread from the oceans to the land.

Answer 19

Around 400 million years ago some vertebrates, such as fish, started developing limbs and other characteristics that allowed them to explore life on land. Lobed-finned fish is a transitional species that shows the link between fish and tetrapods (four-legged animals). It has special features that enable it to move from water to land.

Question 20

Characteristics of lobe finned fish

Answer 20

Lobe-finned fish had bones in their fins similar to land animals, therefore some of these fish may have been able to pull themselves up onto land with their fins. A lobe-fined fish had a stalk-like feature that attached a fin to a body. This lobe fin allowed the organism to support its body and to crawl from the water to land. Its lungs also allowed the organism to breathe air when on land. Lobed-finned fish is a transitional species that shows the link between fish and tetrapods (four-legged animals).

Question 21

Importance of lobed-finned fish

Answer 21

gave rise to tetrapods. transitional species

Question 22

Newtons first law with example

Answer 22

Inertia:
an object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an unbalanced force. An example of this is when your body moves when the car turns a corner.

Question 23

Newton’s second law

Answer 23

an object will accelerate in the direction of an unbalanced force acting upon it. The size of this acceleration depends upon the mass of the object and the size of the force. Force = Mass x acceleration.

Question 24

Examples of Newtons 2nd law

Answer 24

A ball. A ball develops a certain amount of acceleration after being hit. The acceleration with which the ball moves is directly proportional to the force applied to it. This means that the harder you hit the ball, the faster it will move

Question 25

Newton’s third law and identify everyday examples

Answer 25

For every action force, there is an equal and opposite reaction force. For example, when you jump, your legs apply a force to the ground, and the ground applies, and equal and opposite reaction force that propels you into the air

Question 26

Speed

Answer 26

How fast something moves, speed = distance/time

Question 27

Acceleration

Answer 27

The rate at which speed changes in size and/or direction. An object accelerates whenever it starts, stops, changes speed or direction. A force is required to cause these changes.

Question 28

What adds up to give a net force

Answer 28

Forces acting on an object at the same time add up to give a net force.